Mine eyes - a saving test

Mike McCarty · 01-12-2005, 11:04 AM

Mine eyes have seen the glory of the coming of the Lord. Actually, I don't think they have, or if they did, they didn't know how to interpret it.

I get curious about the oddest things. I took three photographs each produced thusly:

Nikon D70, ISO 200, JPEG-Fine-Large, each 3008 x 2000 pixels. This is the largest JPEG file produced by the D70.

Each began the test as a virgin file. Each was then saved 25 times (not in photo shop but a wannabe). Each was then cropped to 400 x 600 pixels. I then resized the original image to 400 x 600.

The program would not allow me to save the file unless I had actually altered it in some way. So each time I made an indistinguishable mark before saving.

Each of the large images below are only resized to 400 x 600 and otherwise untouched (except for the one save to resize). The first cropped image represents the virgin file after it was saved 25 times and then cropped to what you see. The second cropped image is the virgin file cropped and saved once.

Mike McCarty · 01-12-2005, 11:07 AM

Next image ...

Mike McCarty · 01-12-2005, 11:09 AM

And the third and final ...

John Reidy · 01-12-2005, 09:46 PM

Incredible (I mean it's really neat - not unbelievable).

The differences on my screen @72 dpi are nearly if not impossible to see. Is the same true at your higher resolution?

I purchased the camera and 2 lenses from a camera store in NY and won't receive it until next week. I am still expecting to buy an additional card (1G 40x) and a remote. I can hardly wait to start experimenting.

Mike McCarty · 01-12-2005, 10:10 PM

Maybe there is some part of this that I don't grasp. I have always heard that saving JPEG images would eventually sap the life out of them. They continue to be compressed and have data thrown out after each successive save.

So I wanted to see just how far from perfect I could go. You would think that the example above, after being saved twenty five times would show more signs of wear, but I don't see it. Especially after cropping down as far as I did.

I have destroyed many an image, but it has been through the over manipulation of something that started out being poorly exposed. It would seem that only the act of saving a JPEG that was properly exposed does not create the kind of deterioration that I expected to see.

If someone can point out how I have misunderstood this issue I would like to hear it.

Mike McCarty · 01-12-2005, 10:16 PM

It would have been interesting to see a RAW image as part of the control group. I would guess that the quality of the image would be noticably better at the tight crop.