Output image file quality / JPEG artifacts
Standard Test Scene
The 7D provides three different image sizes in combination with three JPEG compression settings. In addition of course you have a RAW file capture option (Minolta's own .MRW & .THM format) and a RAW + JPEG option which allows you to capture one RAW and one JPEG with each shot, JPEG compression is always Fine but the image size can be selected.
Below you will find crops of the same 240 x 180 portion of the center of a sequence of images taken at some of the available combinations of image size and quality. Crops shown are at 100%, saved as extremely high quality JPEG. The RAW file was converted to a TIFF using DiMAGE Viewer 2.3.7 (as provided in the box).
|3008 x 2000 RAW
8,984 KB .MRW + 44 KB .THM (not for download)
|3008 x 2000 JPEG Extra-Fine
4,740 KB .JPG
|3008 x 2000 JPEG Fine
2,634 KB .JPG
|3008 x 2000 JPEG Standard
1,490 KB .JPG
2256 x 1496 JPEG Extra-Fine
Most recent digital SLR's seem to feature a very low compression JPEG mode, the 7D is no exception with its Extra-Fine compression you get images which are as good as lossless (essentially TIFF quality). Next down is Fine mode which delivers full resolution JPEG's at about 2.5 MB, this would be my choice as it still doesn't exhibit any JPEG artifacts and yet is relatively economical on storage. Konica Minolta's RAW format does appear to be packed well (no wasted bit space) and the .MRW files themselves can vary in size (although not by much, they're nearly always around 8.8 MB). If you'd like to capture smaller sized images (not sure why though) the 7D's downsampling interpolation appears to be good with clean images and no jaggies.
The 7D provides for the selection of output color space, you can select from sRGB Natural (neutral balance), sRGB Natural+ (more contrasty, more saturated) or Adobe RGB. Images taken in the Adobe RGB color space have a .JPE filename extension (which could be confusing for some photo applications, although most popular ones do appear to understand it). In addition Adobe RGB images have a proper embedded profile. Place your mouse over the label below the image to see the GretagMacbeth ColorChecker chart taken in each color space.
|sRGB Natural||sRGB Natural+||Adobe RGB
(converted to sRGB)
Color space: CIE u'v' Color Distribution chart
Note that in these samples the Adobe RGB image has not been converted to sRGB and so to view it correctly you will have to load it into a color space aware photo application and assign the Adobe RGB color space. Below each sample is the CIE u'v' Color Distribution chart; larger gray triangle approximately represents the range of color which the human eye can resolve, the inner triangle the available gamut in each color space (sRGB or Adobe RGB).
|sRGB Natural||sRGB Natural+||Adobe RGB|