Output image file quality / JPEG artifacts

Standard Test Scene

The 750Z provides six different output image size settings, and another six if you switch to 3:2 aspect ratio. These can be used in combination with three JPEG compression settings (indicated by a number of stars) additionally there's also an uncompressed TIFF option. It's a pity Pentax didn't include a RAW capture mode. It's worth noting that the 750Z's maximum resolution is 3056 x 2296 which is very slightly smaller than most other seven megapixel digital cameras.

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.

3056 x 2296 TIF (Uncompressed)
20,668 KB .TIF (not for download)
3056 x 2296 JPEG
3,626 KB .JPG
3056 x 2296 JPEG
1,381 KB .JPG
3056 x 2296 JPEG
901 KB .JPG
2592 x 1944 JPEG
2,567 KB .JPG
2048 x 1536 JPEG
1,577 KB .JPG

1600 x 1200 JPEG
727 KB .JPG


The three star setting has very low compression and no artifacts, dropping down to two stars doesn't appear to have a major impact on the visibility of JPEG artifacts or image detail (one star however does). For the smaller image sizes the downsampling algorithm looks good, clean images with no jaggies.