Canon T2i High ISO RAW
Canon EOS T2i High ISO RAW Image Quality
We've recently started looking at RAW files converted with dcraw, an excellent freeware raw converter. dcraw usually offers timely support for the latest cameras, but more importantly, it does not apply any noise-reduction, sharpening or other corrections such as geometric distortion correction to the output files. (We found that Adobe Camera Raw still applies some limited noise-reduction when its NR settings are set to zero, and it also applies other corrections depending on the make and model of the camera). There will always be differences between RAW converters, in terms of the sort of demosaicing algorithms they use (the processes by which they convert the separate Red, Green, and Blue data sets to an array of full-color RGB pixels), but dcraw seems to use a fairly generic algorithm that delivers good sharpness with relatively few artifacts, and can be counted on to not apply any noise reduction if you don't want it to.
Below are crops from Canon T2i high ISO RAW files compared to RAW files from other SLRs such as Canon 7D, Nikon D90 and Pentax K-7, converted with dcraw.
Here, we can see that the relative performance in this group echoes that of the JPEG results, though results are a little closer than you'd think. The 12.3-megapixel Nikon D90 comes out on top (but just barely) and the 18-megapixel Canon T2i follows a close second, except at ISO 6,400 where the T2i pulls ahead. Again, the Canon T2i performed better than its more expensive sibling, the Canon EOS 7D, showing less noise particularly in the red channel where it doesn't show nearly the number of bright clusters of red pixels the 7D does at higher ISOs. The T2i also does better than the 14.6-megapixel Pentax K-7. Impressive.
Here's a comparison with some less expensive SLRs:
In this group, the 12.4-megapixel Pentax K-x performs the best of the bunch in terms of noise, however the Canon T2i does quite well against its predecessor, the 15.1-megapixel Canon T1i, as well as the 12.3-megapixel Nikon D5000. Very good performance from the Canon T2i, especially considering it has the highest resolution and therefore the smallest photosites of the group.