Hi Roy, Sorry. That's been the conventional wisdom for some time. However, it is not correct. Unfortunately it requires some math to understand the reasoning. The JPEG algorithm mimics the human visual system. The RGB file is converted to YCbCr in JPEG. (It's similar to LAB in that it has one Lightness channel and two color channels.) The human visual system is by far more sensitive to Lightness than to color. Thus the loss of 50% of the color pixels is usually not even noticed. Then the algorithm proceeds to compress color much more than lightness. Thus, FOR THE SAME QUALITY 4:2:2 will give a smaller file size in bytes than 4:4:4. 4:2:2 is the default in both Photopaint and Photoshop for this reason. You can check this out somewhat in the Lab mode. Blur the color channels. Sharpen the lightness channel. Usually, the image will improve. Phil Of course, there are trick files for which this is not true. Phil
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