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Old Jul 8, 2003, 7:09 PM   #1
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Default Compressed vs uncompressed digital format

I have been researching a new digital camera and was down to the Olympus Stylus 400 or the Canon S4000 until I found that, while both are 4.0 megapixel cameras, neither one supports an uncompressed picture format. I am interested in a good, small camera with high resolution. I find with my 2.0 megapixel camera, I most often use the uncompressed TIF format when I think I might enlarge a shot.

What am I losing without this capability?

Does the increased resolution make up for the loss of the TIF capability?
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Old Jul 8, 2003, 9:41 PM   #2
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Default Re: Compressed vs uncompressed digital format

Originally Posted by hbs
uncompressed TIF format when I think I might enlarge a shot.

What am I losing without this capability?

Does the increased resolution make up for the loss of the TIF capability?
With my filmscanner and both digital cameras I have used, extensive tests have demonstrated to me that TIF is a quite unnecessary nuisance, for all my uses, which include big enlargements. This has always been at more than 2Mpix; my OlyC3020Z was 3Mp.

You can try it for yourself by taking the same shot on a tripod in all the camera's compression modes, or by taking an original tif, and jpg-saving at various compression levels. Then inspect them alongside each other in your image viewer, hugely blown up so that you can see the pixels. I find that the tif and the jpegs are very-near-identical, pixel for pixel, when viewed at high magnification. Remarkably, this is true even for the 'economy' mode on my 5Mpix Casio QV-5700, so I use it routinely.

If you engage in jpeg-resaving jpegs again and again, you'll get horrible results, but if you always start with the original file you'll be fine. High quality jpeg compression does very little to the image.
If you *really* want tif, shoot a fine-quality jpeg and then convert it afterwards.

Most image-processing packages seem to offer approx '90% jpeg quality', or 'compression level 10' by default. I use Paint Shop Pro compression level 13 routinely.

I'm sure many folk will disagree, so I look forward to seeing their evidence of the necessity of TIF.
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Old Jul 8, 2003, 10:54 PM   #3
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Alan, I'm with you. I have done tests with my Olympus E20 and my Nikon CP 950, comparing uncompressed TIFFs with hghest-quality JPEGs, and even blowing the images up in Photoshop so you can see every pixel, I find it hard to see the difference.
I use the highest resolution and highest quality JPEG in both cams. With the E20, which is a 5MP camera, the image files are still almost 4 MB. The real perfectionists insist that you lose image data, even with the highest quality JPEGs, but I guess I'm just not that much of a perfectionist.
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Old Jul 9, 2003, 12:30 AM   #4
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Many people here don't even use the highest quality JPEGs, they use the more compressed HQ format because they can't see a difference in what they shoot, and they can get more pictures on a card, and save SHQ for their best/important shots.

Those two cameras may not have the TIFF format because they don't have enough internal memory to support it (the TIFF to SHQ size ratio on some other Olys are 8 to 1).

The thing that gets me about those choices (besides not finding an S4000 online, assume you meant S400) is that both those cameras have smaller lenses, and separate viewfinders. Personally I wouldn't buy either of them because to me they're toys, something to let the kids take pictures with (although many people like this format camera because it is pocketable)...but ever camera has its pros and cons, and the Stylus does have one thing going for it in that it's weather resistant.
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