Original Review Date: May 6, 1999
||High-end "personal", inexpensive "professional" film scanner|
||Scans 35mm, medium-format, APS, and 16mm!|
||2820 dpi resolution (32.5 meg file from 35mm neg!), 1128 dpi for medium-format scans|
||12 bits per channel, 3.6 Dmax specification|
||Software accommodates beginners AND experts|
||Optional APS adapter|
Minolta is a company with long experience in the world of film, and extensive digital expertise that has so far been applied in the areas of office electronics and imaging (copiers & printers). Recently though, they've been making waves in the digital camera and scanner markets, with their highly capable (and expandable!) Dimage EX 1500 Zoom digital camera, and a whole line of film scanners covering everything from APS to 35mm, to medium-format photography. The aptly-named Dimage Scan Multi is the second of Minolta's scanners we've reviewed, and it offers a unique set of capabilities for the professional photographer.
The Minolta Dimage Scan Multi film scanner is more capable than some of the "personal" film scanners we've reviewed in the past, positioned at the upper end of the "enthusiast" market, but at the low end of the professional market, with a list price as of this writing of $2,499. With its capability to produce high-resolution scans from film sizes ranging from 16mm all the way to 6x9 cm, it is the first effective scanning solution for mid-format photographers for under $3,000. We see the Dimage Scan Multi fitting the needs of users ranging from well-heeled photo enthusiasts, to businesses and professional photographers looking for top performance on a budget. In support of this market, we found the Dimage software did a particularly good job of providing the power demanded by pros, while remaining very approachable for the amateur.
"High Points" Overview
- Supports multiple film formats, from 16mm to 6x9cm(!)
- 12-bit digitization, 3.6 Dmax
- 2820 dpi resolution (small formats), 1128 dpi (medium-format)
- User interface accommodates both beginners and experienced users
- Optional bulk-feeder for 35mm slides
- Optional APS feeder for full-roll scanning
- "Preview" function can pre-scan entire APS film roll
- Hot-cathode light source for long bulb life
The Dimage Scan Multi is a desktop device about the size of a shoebox. It measures 7.9 x 16.1 x 4.9 inches (200 x 410 x 124 mm), and weighs about 13.3 pounds (6 kg). Interface to the host computer is via a high-speed SCSI-2 interface, meaning you'll need to have such a port installed in your computer to use it. (Older Macs typically came equipped with SCSI connections: On the new Blue G3 Macs and Windows machines, you'll need to have an interface card installed. Appropriate cards range from $100 to $300 in price, and one package sold by Minolta includes an Adaptec AHA-2910 card.) The manual lists a number of Adaptec SCSI cards from the 1500 and 2900 series that are suitable. The only restriction seems to be that the 1500-series boards don't work with NEC PC98xx computers.) The standard unit can scan negatives or slides, in either black and white or color, in any of 7 different film formats (counting 6x4.5, 6x7, and other medium-format sizes as separate formats). An optional APS adapter is available for scanning that format, and a bulk-feeder can handle up to 50 35mm slides at a time.
The software CD shipped with the unit supports both Mac and Windows platforms. Standalone scanning applications are provided for both platforms, as well as a Photoshop acquire plug-in for the Mac, and TWAIN drivers for the PC. (NOTE: Minolta specifies that the scanner requires either Windows '95 release 2 (OSR2), or Windows '98. If you're running Windows '95, be sure to check the revision level you have installed.)
Scanning resolution can be as high as 2820 dpi (a 2700-element CCD covering the width of a 35mm slide or negative). This produces maximum image sizes of 2688x4032 pixels for 35mm (32.5 megabytes), or 1920x3328 for APS (19.2 megabytes). For medium-format film, the optics are reconfigured, to stretch the same 2700-element CCD across the 6cm width of the film. Maximum resolution on a 6x9 cm transparency is 2496x3712, producing a 27.7 megabyte file.
A note about scanner resolution, as compared to that of digital cameras: The 10.8 megapixel resolution of the Dimage Scan Multi is even higher than you might expect, when compared to the resolution of a digital camera. Because the scanner's CCD samples each pixel in all three red, green, and blue color channels, it's really equivalent to a digital camera with a 32 megapixel sensor and "striped" color filters. Thus, the first thing most people notice about images scanned from negatives and slides is the extraordinary level of detail captured. That said, the Dimage Scan Multi's scan resolution of 2820 dpi is at the top of the range for 35mm desktop scanners. It's resolution in medium-format mode is less than some of the competition in that marketplace, but you'll pay more than twice as much for competing higher-resolution models.
Another important scanning parameter is "bit depth," a measure of both color accuracy and the maximum density range the scanner can recognize. (8 bits per channel is good, 10 better, and 12 the best you'll commonly find in desktop scanners.) The Dimage Scan Multi captures a full 12 bits per pixel.
Scanner Optics & Light Path
Film scanners tend to take one of two approaches in their optical design, providing either fixed or adjustable focus internal lenses. Given the extreme resolution of most film scanners, we're surprised that the lenses can be designed with enough depth of field to insure sharp focus in the face of minor variations in the film plane position. We're surprised, but the fixed-focus approach does seem to work, as evidenced by the performance of the Minolta's Dimage Scan Speed. The Dimage Scan Multi, by contrast, goes the adjustable-focus route, offering both automatic and manual focusing options. In its default operating mode, the scanner autofocuses before each scan, increasing the scan time, but insuring that the resulting images are sharp.
Normally, the scanner's autofocus system looks at the center of the frame to perform its focus adjustments. Alternatively, you can specify what part of the film you want it to adjust for, or what part of the film you want to manually adjust the focus based on. These are useful features, in that we've sometimes seen scanner autofocus systems outfoxed by low-contrast, or poorly-focused originals. Also, in the case of severely curled film, you may opt for sharp focus in one part of the frame, at the cost of poorer focus elsewhere. The Dimage Scan multi accommodates such situations with the aforementioned option of specifying the point of focus.
Optimum focus can be quite time-consuming to determine on a film scanner, particularly if you have to perform a full scan in between adjustments, to evaluate the results of your tweaking. The Dimage Scan Multi uses a "live feedback" system that we've found very successful on other scanners in the past: A small thermometer-style bargraph display provides a "goodness of focus" indicator, updated constantly as you run the focus control back and forth. A small line on the bargraph display marks the best focus obtained, so you can easily tell when you've passed the point of optimum sharpness. In practice, we never had to resort to manual focus for any of our test scans, but the feedback provided by the Dimage Scan Multi's software made manual focusing very fast and easy when we tried it.
In common with the Dimage Scan Speed, the Dimage Scan Multi uses a special fluorescent light source, producing strong spectral peaks in the red, green, and blue portions of the spectrum. We observed that this diffuse illumination source produced somewhat "softer" scans than some other scanners. The resulting scans had less of a razors-edge on fine detail, but were also much more forgiving of film defects and film grain. A good analogy (for those old darkroom aficionados out there) would be the difference between condenser and diffusion enlargers: The condenser optics tend to produce more contrasty images, but at the cost of greatly enhanced film grain, while diffusion enlargers create a softer look. Note in this though, that while the scans produced by the Dimage Scan Multi have a somewhat "softer" appearance to them, they in fact appear to carry a very high level of detail, as evidenced by the results from our WG-18 (ISO-12233) resolution target scans.
The Dimage Scan Multi uses plastic slide- and filmstrip-holders to carry the film to the scanner. (Glass and plastic, in the case of the medium-format holder.) You first place the media to be scanned into a holder, then insert the holder into the scanner. When you insert a holder into the scanner, it slides easily until it reaches a click-detent. Once it's been inserted to the detent, the transport mechanism pulls it into the scanner body, and moves it back and forth over the fixed CCD sensor to execute the scans.. During scanning, the holder and film is moved past a fixed CCD array.
The filmstrip holder can accommodate strips of 35mm film up to six frames in length, and the slide holder up to four slides. The medium-format holder can accept strips of film several frames long (depending on the specific format chosen), but only a single frame may be scanned without repositioning the film.
We found both all three holders (slide, film, and medium format) to be quite effective and easy to use. The film adapter is hinged, but only to the extent that a plate flips up to expose the side slot into which the film is laid. (Unlike many "clamshell" designs, the slot holding the film is a fixed structure.) The back pressure plate then hinges back down and latches, clamping the film flat. This arrangement did a particularly good job of handling curled or damaged film, regardless of whether the film was curled side-to-side, or along its length. We did find it a little awkward to properly align film that was badly curved along its length though, unless we were willing to touch the film's surface to push it flat while we closed the pressure plate. (This isn't recommended procedure, but a set of soft cotton gloves would eliminate some of the risk associated with it.) We did find one useful technique for making fine alignment adjustments along the length of the film: Holding the film carrier with the clamshell very slightly open, we could jog the film forward or back by rapping the end of the holder gently with a finger or on a padded chair arm. (We don't recommend doing this on a hard surface such as a table top: The plastic seems pretty rugged, but there's no sense tempting fate!) The film-holding slot is about a half-millimeter wider than the film itself, doing a good job of constraining the film position, yet still allowing minor adjustments to be made for fine alignment relative to the limits of the scanning area. We did find that the filmstrip holder crops the 35mm frame very slightly, about 3% in both vertical and horizontal directions by our reckoning. (For some reason, this appears to be a common characteristic of film-scanner filmstrip holders.)
The slide holder is also constructed of plastic, again in a clamshell design. Four recesses are provided in the base to lay the slides into, while the top pressure plate has plastic spring-fingers to apply pressure on the slide mounts, while accommodating a range of slide-mount thicknesses. Depending on your mount (outside dimensions vary slightly), you should have enough space to correct for minor alignment errors between the film and the mount itself, by rotating the slide slightly in the holder assembly. (One or two degrees would be the maximum, but in our experience, this is enough to accommodate the normal range of variation to be found in commercially-processed slides.)
The medium-format holder is a more complex assembly, with anti-Newton coated glass on either side to hold the larger expanse of film flat. This holder is also unique, in providing an explicit means of rotating the film: By releasing a thumbwheel clamp on one end of the holder, the entire clamshell unit can be rotated by about +/- 5 degrees relative to the body of the holder itself. Although we didn't have occasion to use this feature for any of our test images, we feel it's a useful and very worthwhile feature: Even a degree or two of rotation in an image can be glaringly apparent, but it takes a lot of computer power to rotate maximum-resolution images after they're scanned. - Much better to rotate and align things properly before the scan is made!
The Dimage Scan Multi can accommodate frame sizes up to 6x9 cm, which poses a bit of a problem when scanning smaller medium-format frames: In general, to maintain maximum contrast and shadow detail, it's important for a scanner to minimize the amount of excess light bouncing around its interior. Thus, while the Dimage Scan Multi needs a 6x9 cm film holder frame to accommodate its largest film format, this could produce excessive light "flare" when scanning smaller formats, such as 6x4.5. Minolta has dealt with this issue, by providing several thin "masks", made of black plastic with a matte finish, for use with various film sizes. These align over two small pins at the edges of the holder, and serve to mask-off the non-image areas of various formats, minimizing the amount of excess light bouncing around inside the scanning cavity. We discovered though, that the masks also serve another purpose, that of minimizing the problem of so-called "Newton's Rings."
Newton's Rings are caused by the interference of light waves when passing between different media in very close proximity to each other. In the context of scanners, whenever film is pressed firmly against a smooth glass surface, Newton's Rings appear as rainbow-colored rings and wavy lines. So-called anti-newton coatings on the glass can minimize the effect, by presenting a rougher surface to the film, but they are far from an absolute remedy. In the case of the Dimage Scan Multi, we initially tried scanning our 6x7 cm medium-format test film without using the framing masks. (Our reasoning was that we didn't really need them, because the entire image area was filled with film, and hence there shouldn't be any problem with light flare.) We discovered though, that loading film directly into the medium-format film holder without using the framing masks produced fairly severe Newton's rings: When we used the masks, the Newton's rings completely disappeared. Our theory on this is that the framing masks support the glass faces of the clamshell outside the edges of the film frame, relieving pressure over the active area of the film. This pressure reduction allows the anti-newton coating to do its job, and Newton's Rings are all but invisible when the masks are used.
In addition to the medium-format masks provided with the scanner, two additional masks are included, which provide for scanning sleeved 16mm and APS film. These special masks contain an alignment track outside the clamshell area that positions the film, and a standard (albeit smaller) mask window to define the scanning area. Even though the medium-format adapter is used to hold these formats in the scanner, the software configures the scanner's lens system for maximum-resolution operation when working with these film sizes. (This results in resolutions of 1920 x 3328 pixels for APS film, and 1444 x 2166 pixels for 16mm.)System Interface and Included Software
(Much of the following is identical to our writeup for the Dimage Scan Speed (LINK), since Minolta uses the same scanning software across its full line of film scanners. The only substantive difference is that the Dimage Scan Multi software provides options to control the scanner's focusing mechanism, whereas the Dimage Scan Speed uses a fixed-focus optical design. (If you've already read the Dimage Scan Speed review, click here to skip the following section.)
The Dimage Scan Multi uses a SCSI-2 connection to the host computer, providing the high speed data transfer necessary to handle the large amounts of data the scanner can generate. As mentioned previously, one model of the Dimage Scan Multi includes a PCI-bus SCSI card, and Minolta lists several models of Adaptec cards that the unit can be used with. (Adaptec is pretty much the standard for SCSI cards: You can find cheaper ones, but the Adaptec models are more likely to be compatible with a wide range of equipment. Note in particular, that some scanners, CD-ROM drives, and other equipment ships with low-cost SCSI cards included. In many cases, these are "dedicated" cards, that will only run the particular device they're shipped with. If you're buying a card to support the Dimage Scan Multi, take our advice and get a "name brand" Adaptec unit. The hassle you'll save will be more than worth it!)
Once connected to the computer, the Dimage Scan Multi is controlled through an excellent software interface that we'll describe in greater detail below. As noted earlier, the scanner-control software takes the form of standalone applications on both the Mac and PC, as well as a Photoshop plug-in on the Mac, and a TWAIN component on the PC. A particular strength of the Dimage software is the extent to which it provides powerful controls for experienced users, while at the same time offering a simple interface for novices.
Unlike its "little brother," the Dimage Scan Speed, the Dimage Scan Multi software package doesn't include Photoshop LE. The rationale for this is that purchasers of a higher-end scanner like the 'Multi very likely already own a professional image-editing program, making a lower-end package like Photoshop LE superfluous. (For what it's worth, we agree with this assessment.)
Speeds and Feeds
Oh boy, did we mess up on this one! Due to an unusually high level of pending review work, we ran up against the time limit for the loan of the Dimage Scan Multi demo unit. As we hurriedly completed our testing and shipped it back to Minolta, we had a nagging feeling that something was missing. It was -- the detailed speed timings! Because scanner manufacturers tend to be so optimistic in their assessment of scan times, we've taken to carefully measuring how long a real scan takes to complete. (We don't doubt that most manufacturers actually do measure some scans at the times they publish, but they're almost certainly low-resolution scans, and generally include only the actual scanning time itself, neglecting the necessary overhead for autofocus, exposure adjustment, and other pre-scan operations.)
Although we didn't explicitly measure the Dimage Scan Multi's scanning speed, we can report that it is about as fast as any other film scanners we've tested: Its overall operation is very similar to that of the Dimage Scan Speed, which we reviewed earlier, and our sense was that the scanning speed is about equivalent as well. (Click HERE to see the Dimage Scan Speed review.) In the overall scanning process, the Dimage Scan Multi is slightly slower though, since a few seconds are needed before each scan for the autofocus operation. (As noted earlier, the Dimage Scan Speed is a fixed-focus scanner, while the 'Multi employs focusing optics.) We'd guess that each focus operation takes 10-15 seconds or so, not an onerous delay.
Operation and User Interface
Other than the actual scans themselves, most of the story to be told about a film scanner has to do with the software that drives it, and to what extent the combination of hardware and software makes it easy to produce good-quality scans. Accordingly, we'll devote a sizeable of this review to talking about the software that drives Minolta's Dimage family of scanners, and the Dimage Scan Multi in particular.
As noted several times already, we feel that Minolta has done a good job of balancing capability with ease-of-use. This is a difficult equation to optimize, as the needs of "beginners" and "experts" can vary so widely. At the same time, you hope to provide a smooth gradation of capability, not introducing any abrupt hurdles to overcome as users advance in their sophistication. Minolta has accomplished this difficult design goal by providing very basic visually-oriented contrast/brightness adjustments for neophytes, while at the same time offering fairly sophisticated histogram- and tone curve-based controls for those comfortable with more complex adjustments, and who need the control they provide.
As we write this, we're still searching for our "formula" that works best for scanner reviews, but are generally settling on a format in which we step through the scanner controls in the approximate order that a user would encounter them. (For a more complete walk-through of scanner operation, check out Minolta's excellent web site for their scanners: They've put together a remarkably comprehensive "on-line demo" of how the software works.)
The Preview Screen and Command Window
The most basic options and functions of the Dimage Scan Multi scanner are controlled via the Command window, shown below. The Command window contains two list boxes, two status displays, and a total of ten buttons, which we describe below, moving from left to right, top to bottom in the screen shot: (NOTE: This and all screen shots following have been scaled-down to better fit the 'web page -- The actual screens are larger and much more readable!)
- Film Format (List Box) - Options are 35mm or APS
- Film Type (List Box) - Options are Slide Film, Color Negative, B/W Negative, B/W Positive
- Current Job Selection (Display window) - Displays currently-chosen "job type", combining both input and output resolutions. (Translating input resolution (at the film) to output resolution (in the file and on paper when printed) is a tough process to make understandable: Minolta's "Job Type" approach does as good a job of this as any approach we've seen thus far.)
- Job Selection Button - Click for a pop-up menu of currently-defined job types, or create your own.
- Status Bar (Display field) - Displays descriptions of controls as your mouse rolls over them, and gives status information during the scan process. (Very handy for interpreting the sometimes-cryptic button icons, before you get used to them.)
- Index Scan Button (APS Only) - Creates thumbnail-sized index scans of an entire APS film roll.
- Prescan Button (APS or 35mm) - Generates a preview scan of the current film frame or slide. Preview scan sizes can be set to large, small, or automatic. Auto fits the scan resolution to the size screen you're working on. Generally, you'll want the largest preview scan you can get, to help in accurately setting white and black points and in adjusting the tone curves.
- Scan Settings Button - Brings up the Scan Settings window (shown at right), where you can manually adjust the input and output scan resolutions and set the units you want to work in (pixels, inches, or cm). NOTE that you can't set the resolution values when your units are set to pixels, as in the screenshot at right.
- Save Index Scan Button - To save time on subsequent scans (as well as provide a useful index of images on your APS rolls), you can save APS index scans to disk.
- Save Job Button - If you've created a custom Scan Settings configuration, you can save it under its own "job type," for immediate recall later.
- Preferences Button - Brings up the Preferences window, described later.
- Rewind Button (APS Only) - Rewinds APS film back into its canister.
- Help - (If you need us to explain what this button does, you probably shouldn't buy the scanner! ;-)
The preferences window (not shown) controls a number of overall settings governing scanner operation. Most people will rarely need to visit this screen, as the default settings will suffice for many applications. About the only control you're likely to need to change with any regularity is the one for Color Depth, and even then, the non-default settings are likely to be useful to only a small cadre of advanced users. Herewith the Preferences functions:
- Auto Expose for Slides - This appears to be an overall exposure compensation adjustment for scanning very dense transparencies. It made no perceptible difference with our "train" slide though, perhaps because that slide also includes some very light areas.
- Close Driver After Scanning - This will be most useful when using either a TWAIN or Photoshop acquire module for scanning. It will close the scanning window after each scan, returning you to the host application. (Or to the desktop, if you're running standalone.)
- Prescan Size (Options are Small, Large, or Auto) - You can preset the size of the prescan window, or allow the scanning software to size it to your screen automatically. The last is the easiest, the fixed sizes perhaps being useful if you want to be able to see other windows on your desktop while the scanning software is running.
- Color Depth (Options are 8-bit, 16-bit, and 16-bit linear) - As mentioned earlier, the Dimage Scan Speed is a 12-bit per channel scanner. Since computer displays and most programs can only accept 8 bits per channel, what happens to the rest? Normally (in 8-bit mode), the scanner and scanning software translate the 12-bit data down to the 8-bit final data size, in effect "choosing the best 8 bits." For most uses, this is the easiest and most direct thing to do. For difficult subjects with particularly wide dynamic ranges though, you may want to employ some unusual tonal mapping, to preserve both shadow and highlight detail, or experiment with different approaches after the scan is complete. For these situations, Minolta provides the ability to capture all 12 bits per channel, and store them in a file. Since the TIFF file format only recognizes either 8 or 16 bits per channel, the option which preserves the full 12 bits of original data is labeled "16-bit," even though only 12 bits per channel are actually being stored. It's a little harder to understand the need for the "16-bit linear" option, but perhaps it has some use in scientific applications. What it appears to do is to turn off the analog "gamma" adjustment that takes place prior to the digitization of the image data. The same raw data is being captured, but the distribution of bits across the tone curve is very different. (In general, dark areas look VERY dark with the 16-bit linear option enabled.) As we said, this doesn't appear to be terribly useful for general photographic applications, but could find some use in photogrammetry. NOTE: We're not sure if it was a bug in the version of software we tested, or a misunderstanding of its function, but we weren't able to properly read any of the 16-bit files we saved from the Dimage Scan Multi into Photoshop.
APS Settings - not having had the APS attachment to play with, we didn't have an opportunity to experiment with these, and the main manual offered no description. Below are our "best guesses" as to what they do:
- Index Scroll Direction (Options are Horizontal or Vertical) - APS pre-scans produce arrays of thumbnail images. This option simply selects whether the display is set to scroll horizontally or vertically as you move through the array of images.
- Index Scan Priority (Options are Speed or Quality) - With up to 40 frames on a roll, you may sometimes prefer a "quick and dirty" pre-scan in order to view all your images quickly. At other times, you may want a higher-quality prescan, to facilitate image adjustments prior to the high-resolution scans themselves. (Note that you don't have to pre-scan the entire roll, if you know which image you're interested in, based on your APS index print: The software apparently displays blank thumbnails as soon as the roll is loaded, allowing you to choose the image you're interested in, based on frame number.)
- Max # of Frames - We're not sure what this control is for, unless it's to restrict the pre-scan operation to the first few frames of a roll
- Auto Film Rewind - Apparently an option to rewind the film back into the cartridge after the scanning is completed.
- Rotate All Frames 180 degrees - Depending on how the APS cartridge loads into the camera, rolls from some models could come out "upside down." This checkbox avoids the need to laboriously flip every individual frame separately.
This window (shown below) is "home base" for the scanning process. From here, you'll launch off into other functions within the software, to adjust color balance, contrast, or tonal range. Controls here also adjust preview orientation, data readout, and exposure parameters for sequential scans. See the text following the screen shot for a description of the individual buttons and controls.
Here are the Prescan Window controls, reading from left to right and top to bottom, for all the buttons down the left-hand side of the screen:
Orientation and Viewing Controls
- Rotate Left Button - Rotates preview (and final scan) 90 degrees to the left. (Counterclockwise)
- Rotate Right Button - Rotates preview (and final scan) 90 degrees to the right. (Clockwise)
- Flip Horizontal Button - Flips picture horizontally.
- Flip Vertical Button - Flips picture vertically. (The two "flip" buttons find frequent use when flipping the slide or film carrier to scan frames at both ends.)
- Full-Screen View Button - Enlarges the currently-selected region of the pre-scan window to full-screen size. (Note though, that this enlargement is only a pixel replication, so it becomes rather pixellated when smaller regions are magnified.)
- Zoom Button - Zooms in on a selected area of the pre-scan window.
- Auto Exposure Lock Button - The scanner normally performs an autoexposure adjustment prior to each scan. Sometimes, you'll want to treat all slides or negatives of a group the same (for instance if they're going to be used together to make a panorama). To accommodate this, click the Auto Exposure Lock button after pre-scanning the first image. This will lock the exposure settings to those calculated for the first image of the group. (NOTE though, that this doesn't lock or save any exposure adjustments made with the Histogram, Variations, or Tone Curves controls.)
- "Grab" Button - This button turns the cursor into a "grabber", that lets you drag the pre-scan image and drag it around, to see various areas when the pre-scan image has been enlarged with the Zoom Button.
- Manual Focus Button - Changes the cursor to a crosshair. Clicking on the preview image initiates a manual focus operation, centered on that part of the film frame. A bargraph display is presented, showing current focus level in arbitrary units, with the level corresponding to the best focus achieved shown as a vertical line across the graph. Manipulating the on-screen focus slider control actuates the lens assembly inside the scanner, adjusting scanner focus. (Not shown in this screen shot, which is from the Dimage Scan Speed - sorry...)
- Automatic Focus Button - Changes the cursor to a crosshair. Clicking on the preview image initiates an automatic focus operation, centered on that part of the film frame. (This could be useful for badly-curved negatives, if you wanted to crop into the image, and needed to focus precisely on just that specific area.) (Not shown in this screen shot, which is from the Dimage Scan Speed - sorry...)
Image Adjustment Controls
(Buttons in this group take you to other screens, to adjust the scan settings.)
- Variations Button - This leads to a screen (described in more detail below), where you can quickly adjust brightness and contrast, by the simple process of repeatedly choosing the most appealing of 8 alternate versions of the image. - An excellent tool for novices to quickly adjust their images.
- Tone Curves Button - Probably at the opposite end of the ease/power spectrum from the "variations" control, the tone curves screen (described in more detail later) provides the powerful ability to edit the tone curves for both the image as a whole, as well as the individual red, green, and blue channels.
- Histogram Button - This is our favorite scanning/image adjustment tool! (Also described in more detail later.) To our mind, histogram-based image adjustment offers the best tradeoff between ease of use and power for most mid-level users.
- Reset All Button - This button resets all the image adjustments to their default settings, letting you quickly back out of a set of adjustments and return to "zero."
At the bottom left-hand corner of the Prescan window, there are two sets of readouts, one showing the dimensions of the current cropping frame (in mm), and the other the RGB (or CMY) values of the point under the cursor in the preview window.
It's often difficult for novices to decide what to do to an image to make it look better. More contrast? Less brightness? A little of both? Frequently, after playing with an image for a few minutes, you end up with something that looks worse than when you started! Yet, even the rankest amateur can generally tell whether picture "A" looks better than picture "B". Taking advantage of this, Minolta offers a "Variations" tool, as shown in the screen shot below. Here, the current contents of your cropping frame are displayed in the center of a matrix of images, with those around the edges of it representing the effects of more or less contrast or brightness. (Contrast variations run vertically, brightness variations horizontally.) If you decide you like one of the variations presented more than the current image, just click on it: It becomes the new reference sample, and the variations adjust to reflect changes relative to the new center image. By continuing to click on the image that you like best, you can quickly home in on the optimum brightness/contrast setting.
After you've set the contrast and brightness, you can then correct the overall color balance of the image, by adjusting the R, G, and B slider controls at upper left. Always wait to adjust the color until after you've made the brightness & contrast changes though, as you'll frequently find that perceived color problems diminish once the brightness and contrast are properly set.
The "Variations" screen also has a button that enlarges the current selection to full-screen size, making it easier to assess the current picture quality. We felt that this feature was marred slightly by the fact that the enlarged image is only a pixel-replicated copy of the original area, which can lead to rather pixelated images if your cropping frame is small relative to the overall film area.
As we noted earlier, Histogram adjustments are by far our preferred method for quickly correcting tone and color problems in digital images! For those not familiar with histograms though, a brief explanation would probably be in order.
A histogram is simply a graph of how many pixels in an image have each possible brightness value. A large peak on a histogram graph means there's a lot of pixels (a large area) with roughly the same brightness values. Likewise, if the histogram curve is near zero, it means relatively few pixels have those brightness values. To understand how this helps image adjustment, we've included a couple of sample images at right, showing two images set up with different brightness and contrast settings, and the histograms associated with each.
Dull, flat image has a compressed histogram, with no information above the midtone level in any channel.
In the first sample, we have a rather low-contrast, dark image. Low contrast means that there's not a great deal of difference in the brightness values between the brightest and darkest pixels. "Dark" means that the bulk of the pixels in the image have fairly low brightness values. In the histogram curves for this image, note how the right-hand side of the curves (high brightness values) are flat, because there aren't any pixels with those brightness values. Also, note how the histogram curves occupy a fairly small amount of the horizontal space allotted to them.
Well-balanced image shows full range of tonal values in histogram, in all channels.
By contrast (no pun intended!), observe the image above: Contrast and brightness are about right, and the results are readily evident in the histogram curves for it. Notice how the curves occupy much more of the available horizontal space, meaning that pixel values are spread much more evenly across the available tonal range. Notice too, how you can even tell about color balance from histogram displays. Notice the large "hump" near the middle of each curve? What object in the image do you suppose this large group of pixel values corresponds to? (It's the background.) Now, if we want the background to be a neutral gray, what do you suppose the display would look like. (The peaks in red, green, and blue would all line up with each other, meaning that the average R, G, and B values would be about the same.) Can you guess how the color balance needs to be adjusted to achieve this?
Notice the sliders under the individual histogram curves. These are used to set the brightness values the scanner will consider to be the minimum (black), maximum (white), and a middle value (gray), for each of the color channels. If you move the "black" slider up from the leftmost position, you're telling the scanner to treat that value as "zero" for the color channel involved. Any values darker than that will also be treated as zero, and values brighter than it will be proportionately stretched downward so that the brightness values will extend smoothly down to zero. Likewise, the "white" slider on the right sets the value that will be considered as a maximum, and mapped to a digital value of 255. Anything brighter will also be set to 255, and darker values will be "stretched" smoothly. The middle slider sets the value that the scanner will put in the middle of the brightness scale (the "50%" point). Anything brighter than the level set by the slider will be made brighter than 50%, anything darker will be made darker. Thus, to lighten the image overall, you'd move this slider to the left, so that more of the brightness values would be pushed above the 50% point. (This all sounds more complicated than it is: You'll figure out what the sliders do after just a couple of minutes of playing around.)
The histogram screen includes "before" and "after" previews, and a number of controls for adjusting the image. At middle left are three of the most immediately useful tools, the eyedroppers for setting white, black, and gray points. If you select the black eyedropper button, and then click on a point in the left-hand preview window, that point will be set as the "black" point, and the individual red, green, and blue black-point sliders will all adjust automatically to make it so. Likewise, selecting the white eyedropper button and clicking in the left-hand preview window will set that point as the "white" point, moving the red, green, and blue white-point sliders as needed. (Anyone want to guess what the gray eyedropper button does?) In practice, you'll find that the eyedropper controls offer a very quick way to color-balance many problem images in a matter of seconds.
Part of the beauty of the Dimage Scan's histogram screen is the way it shows histograms for all three color channels separately, yet also allows you to operate on all the channels at the same time, if you wish. By default, you can adjust any of the slider controls independently of any other. What if you want to make an overall adjustment to the image as a whole, though? In the lower left-hand corner, the button with the three colored bands on it is the "RGB synchro button." Clicking this button locks the sliders for the red, green, and blue histograms together, so that moving any one of them moves the sliders for the other two colors the same amount.
The other control buttons in the lower left-hand corner let you see the effects of your adjustments on the histogram, as well as save and retrieve complete sets of adjustments once created. This last ability is a particularly welcome one, as many lower-end scanners don't permit you to save adjustments for later use. Often, we find ourselves wanting to save a group of settings before engaging in further experimentation, so we have a known good point to return to if our twiddling goes awry. Also, you may have a group of photos shot under similar conditions that would all benefit from the same treatment.
One odd point about saved and subsequently recalled histogram corrections though: When the DSM Scan software applies a previously saved correction to an image, it does so on top of whatever correction may currently be in effect. Thus, the effects of recalled corrections are cumulative with any you've already applied. If you want to return to a prior state, you'll need to reset all corrections (using the Reset button) before applying the saved settings. (This isn't any sort of a problem, but was different than how we expected the saved settings to work. We're passing the information along here to hopefully save our readers a few minutes of puzzlement when they encounter the behavior for the first time.)
A full treatment of histogram-based tonal adjustments is far beyond the scope of this review, but we encourage users to spend some time playing with the controls on this screen: They're simple to master, but quite powerful to use.
Tone Curve Adjustments
The tone curves window (shown below) offers a set of controls that are at once easier to understand than those of the histogram display, yet considerably less straightforward to apply effectively. Even here though, minor tweaks by Minolta contribute greatly to ease-of-use.
In concept, tone curve controls are as simple as can be: They're nothing more than a graph of output brightness values against input brightness values. Essentially, they say "whenever you see brightness 'x', replace it with brightness 'y'. The input brightness values (those of your original image) are arranged along the horizontal axis of the graph, and the output values (those your image will come to assume) are arranged along the vertical axis. Again, the easiest way to understand how a tone curve works is to play with one. A little experimenting will reveal that a steeply sloping curve produces high contrast, while a flatter one produces less. Likewise, a curve bulging upward results in a brighter image overall, and one drooping downward makes for a darker one. The Dimage Scan software lets you adjust either the overall RGB curve, or each of the color channels (red, green, and blue) individually.
Tone curve controls let you adjust parts of the tonal scale, without affecting others. As such, they're more powerful than the histogram controls, but you have less feedback as to what parts of the image you're affecting, and it's much easier to get lost in your adjustments with them. Experienced graphics professionals rely on tone-curve adjustments almost exclusively though, because they provide such a high degree of control over the tone and color balance of images.
The tone curve controls in the Dimage Scan software work like those of most any high-end image editing program: You can click any point on the curve and drag it, and the rest of the curve will bend smoothly to pass through the point you've defined. You can set multiple control points by clicking on more than one part of the curve. You also have the ability to draw your own curve, using a pencil tool, allowing you to create abrupt discontinuities if desired. Minolta added a unique twist to the tone curves though, in the form of white and black-point eyedropper controls, which work in the same way as the equivalent controls on the histogram screen. While a seemingly minor point, the eyedroppers can quickly make gross adjustments in the overall tone and color balance, and provide a good jumping-off point for your own finer adjustments.
As always with Imaging Resource reviews, we encourage you to let your own eyes be the final judge: Look at the sample images, download them, print them out on your own printer, and decide for yourself how well the Dimage Scan Multi would meet your requirements!
Overall, the Dimage Scan Multi turned in a very competent performance, easily besting the current crop of "consumer" film scanners in most areas. (As you'd expect from a scanner selling for nearly $2,500, vs as little as $300 for the low-end devices.) Particularly in contrast to the digital cameras that constitute the other major review focus of this site, readers are sure to be impressed with the incredible amounts of detail a scanner like the Dimage Scan Multi can extract from a slide or negative.
We found that the Dimage Scan Multi produced very good scans with the default settings, and excellent ones with only minor tweaking of the scan controls. Behavior overall was very reminiscent of its "little brother," the Dimage Scan Speed: On the PC, the default settings tended to produce slide scans that were slightly dark, but a minor bump of the midtone point using the histogram control would quickly bring the overall tone into a reasonable range. By comparison, scans of color negatives were a bit light, but a minor drop of the midtone point tended to quickly compensate. Color balance overall was quite good, although by default, the scanner seemed to like to add a bit of magenta to things (red and blue together). We suspect this might be an attempt to compensate for typical computer monitors, which tend to have a very bluish white-point, frequently as high as 9300K. Again, it wasn't too difficult to compensate for this tendency, and the ability to save and recall sets of tone and color corrections was a valuable feature. Overall color accuracy was excellent, with color saturation just a notch away from the best we've seen to date (May, 1999). On the Mac, the scanner's default settings produced lighter scans, requiring less adjustment. (This is doubtless due to differences in the standard CRT gamma settings on the Mac vs PC.)
Resolution of the Dimage Scan Multi was excellent, but hard to "call" based on our standard test targets. The reason for this is that an unusually low level of "aliasing" had us convinced we could easily see at least some detail in the WG-18 target all the way out to 1800 lines per picture height (l/ph) in both horizontal and vertical directions. Conservatively stated, the scanner clearly resolves the target out to 1400 l/ph, and a good bit beyond. With our 6x7 test film, we found resolution was slightly less: Still very clean at 1400 l/ph, but falling off somewhat more rapidly as higher frequencies were approached.
The USAF resolution target gave (as usual) more conservative resolution figures, with the scanner resolving fairly cleanly down to 35.9 line pairs/mm (912 line pairs/inch), and with increasing aliasing below that level. Curiously, the target element at 57 lp/mm (1448 lp/inch) came out remarkably clean, although we suspect that this was just a coincidence due to the lucky alignment between target elements and scanner pixel positions. With natural subjects, the scanner's fluorescent light source produced a somewhat softer, less grainy look than some other units we've tested, although there seemed to be no loss of detail information in the scans associated with this softer "look".
See for Yourself!
Take a look at the test images from the Dimage Scan Multi, download them, print them out, and see if this scanner meets your needs!
In the Dimage Scan Multi, Minolta has crafted a combination of capabilities and software features into a unit that produces good image quality with a minimum of tweaking. Even better, when it does come time to manipulate color and tone, the software controls provide a full range of capabilities, satisfying users ranging from rank amateur to experienced color professional. The biggest news with it though, is undoubtedly its ability to produce high-quality scans from medium-format transparencies and negatives, at a very affordable price. For professionals and serious amateurs working with medium-format film, the Dimage Scan Multi opens the possibility of in-house scanning at an unprecedented price point.