Jack, Not sure I understand your question.
A 6.1 Megapixel image can be represented in files of varying size depending upon the pixel depth as well as how much and what type of compression you apply. A 1.5M JPEG rendering might have substantial compression artifacts, or it might have very little, depending upon the image and the quality of the JPEG compressor.
Curious about how much difference one might see, I took the photo I posted recently of my brother (a full 6Mpixel uncompressed Photoshop image, 34.2Mbytes in size) and rendered it at HIGH quality JPEG compression to 1.5Mbytes file size. I then created a new file with a pixel difference calculation. Judging by what I see in that difference file, the difference in a print up to A3 Super in size is going to be pretty small.
However, if I'd captured the image as an in-camera JPEG and done all my editing in [EMAIL PROTECTED], I suspect the total difference would be much greater. There's no question that the original, not-JPEG, uncompressed image will print better too, the difference is purely a matter of what you consider as significant.
Godfrey
