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Output image file quality / JPEG artifacts


Standard Test Scene

The DiMAGE A2 provides five image sizes from 3264 x 2448 (full native eight megapixels) down to VGA, it also provides a 3:2 aspect ratio image size of 3264 x 2176. These selectable image sizes can be combined with an output file format of JPEG (three compression levels) or TIFF (as I have noted in other reviews I really think TIFF has had its day, especially in a camera which supports RAW). As has become standard at this level the DiMAGE A2 also has a RAW output option (Minolta .MRW file format), additionally and uniquely in a camera of this type the A2 also provides a RAW+JPEG mode.

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 Konica Minolta DiMAGE Viewer 2.32 (supplied with the A2).

3264 x 2448 RAW (Uncompressed)
12,375 KB .MRW (not for download)
3264 x 2448 TIFF (HI)
23,520 KB .TIF (not for download)
3264 x 2448 JPEG Extra-Fine
4,976 KB (1.6:1 compression, 5 bpp)
3264 x 2448 JPEG Fine
3,641 KB (2:1 compression, 4 bpp)
 
3264 x 2448 JPEG Standard
1,796 KB (4:1 compression, 2 bpp)
 
2560 x 1920 JPEG Extra-Fine
3,046 KB (1.6:1 compression, 5 bpp)
2080 x 1560 JPEG Extra-Fine
2,231 KB (1.6:1 compression, 5 bpp)
1600 x 1200 JPEG Extra-Fine
1,476 KB (1.6:1 compression, 5 bpp)
640 x 480 JPEG Extra-Fine
367 KB (1.6:1 compression, 5 bpp)

For most everyday work the JPEG Fine setting appears to deliver high quality results with no visible JPEG artifacts. For 'virtually lossless' quality which is indistinguishable from TIFF Konica Minolta provide the very low compression Extra-Fine setting. Downsampled (smaller sized) images were good down to 1600 x 1200, below this they did have a slightly jagged appearance.


Color mode / color space

Just like the DiMAGE 7Hi and DiMAGE A1 the new A2 provides a range of selectable color modes from the camera menu which provide you with a choice of two sRGB color modes and one Adobe RGB. Adobe RGB is available in two different options with out without embedded ICC color profile, the later of which will be automatically recognized as Adobe RGB by ICC aware applications such as Adobe Photoshop. Embedded Adobe RGB files are saved with the .JPE extension instead of .JPG.

GretagMacBeth ColorChecker samples

Place your mouse over the labels below the image to see the GretagMacbeth ColorChecker chart taken in each color space.

Natural (sRGB) Vivid (sRGB) Adobe RGB *

* Note that the Adobe RGB image has been converted to the sRGB color space
for correct display on your web browser.

Test shot samples

Below each sample is that image's 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).

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. Remember to view the Adobe RGB image correctly you must load it into a color space aware application such as Adobe Photoshop and ensure the Adobe RGB color space is assigned.

Natural (sRGB) Vivid (sRGB) Adobe RGB
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