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Old Jan 19, 2003, 9:47 PM   #21
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TonyG,
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can't wait for a 5mb tiff to save
Yeah, my E20 is fairly slow saving to the card anyway, even for the JPEGs, but it takes FOREVER for TIFFs. The E20 has a buffer, though, so you can take four shots In JPEG SHQ mode, as fast as you can shoot before the buffer is full. The slow write to memory is about the only thing about the E20 I don't like, but it has rarely been a problem. Otherwise, it's a great camera.
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Old Jan 20, 2003, 12:03 AM   #22
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Hi Bert, you said: but if you use the highest quality (lowest compression) JPEG that your camera offers, the loss is minimal My shq jpeg file size averages about 1700 kb. The TIFF file size is over 12,000 kb. That's a significant difference, the highest jpeg setting has a lot less information than the TIFF...
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Old Jan 20, 2003, 12:42 AM   #23
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My shq jpeg file size averages about 1700 kb. The TIFF file size is over 12,000 kb. That's a significant difference, the highest jpeg setting has a lot less information than the TIFF...
Compression doesn't mean you lost any information. The simplest way to explain compression is if you have a row that is blue red red red red red red red red red red green green green green blue, you could say blue 10red 4green blue. The second line is smaller/shorter, but did you lose any information? No. This is obviously a very over-simplified example, but thats the basic way compression schemes work. If you use a fax machine regularly you probably noticed that the areas which are all white (or all black which is rare) zip through the scanner, but the area with pictures or text slow way down. This is because the compression used by a fax machine works like the example I used. No data loss, just eliminating repetition.
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Old Jan 20, 2003, 2:53 AM   #24
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jbailey,
JPEG compression doesn't work that way, unfortunately. It deals in square blocks of pixels with approximately the same color values...the higher the compression ratio, the larger the blocks. It assigns the same value to all pixels in the block. If you go to very high compression (small file, lower quality) you can actually see the blocks if you magnify the image in an image editor like Photoshop. Some pixel data is lost with this method, although it is a very efficient compression method. You can also see distortion along contrast edges. If you use a low "compression ratio" the blocks are very small, but they are still there.
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Old Jan 20, 2003, 3:04 AM   #25
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Johnny,
12 Mbytes to 1.7 Mbytes...that's pretty severe compression, about 1:7. You will lose some picture quality with that. On the E20, SHQ is 1:2.7. I think my Nikon CP950 is about 1:8 on the FINE setting, which is the best JPEG quality. I must admit, I have trouble seeing the difference between JPEG FINE and uncompressed TIFF, though.
As I said before, it depends on what you want to do with the image. If you want a tack-sharp 8x10 portrait (some women like them a little soft, though ) TIFF is probably the answer. By the way, the E20 compresses TIFF images. The numbers you gave indicate that your camera does not compress, I think, if you have a 4 megapixel camera. (4 megapixels x 3 bytes per pixel = 12 megabytes)
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Old Jan 20, 2003, 4:20 AM   #26
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Thanks Bert, loved the 'soft image' according to women dig! Yes, I'm using the Oly C-4000 and I almost exclusively use shq because I have a lot of memory available, but like you said, and I said, I think, when I want a 'pin-up' 8x10 or larger, I use the Tiff just to be safe...my camera sure takes a long time 'saving' that image, though!
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