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Too many megapixels?

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#41 Glasseye Snapper

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Posted 20 December 2005 - 12:11 PM

I know this is a very old thread but it makes interesting reading. No-one seems to mention bit-depth. When I started using digital I supplied 16-bit files but was told by an unwilling-to-modernise production man that the bit-depth was not sufficient.
It now seems that printers actually use 8-bit files so once you've done you converting to TIFF, supply as 8-bit files and you will get more files in the space. As I understand it, (and I may be wrong) bigger 16-bit files will simply be converted before printing.


Hi John,

It isn't clear to me if you are talking about bits-per-pixel or bits-per-color. There are 16 bit-per-pixel image formats that basically use 5 bits each for red, green & blue (so really only using 15 bits per pixel). The producting guy you mentioned may indeed have complained about that not being enough as 8 bits-per-pixel (for 24 bits per pixel) is the norm. This may be the 8-bit file the printer was talking about. There are also real 8 bit-per-pixel format but they typically (always?) use a colour table with up to 256 colors. Each 8-bit pixel then just specifies which color out of the table to use.
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#42 John Bantin

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Posted 21 December 2005 - 03:23 AM

I am simply talking about whether you choose (eg in Photo-shop) whether to save as a 16-bit tiff or an 8-bit tiff.

What the production man really did not like was the icon supplied with files from my scanner when used as a stand-alone application! By going into Photoshop the files look exactly like those from my digital-capture files taken the same way, so they are now OK!

However, the point I was making is that a file finally saved in 8-bit is a lot smaller than one saved in 16-bit so when someone stipulates a file size for repro we need to know what bit-rate too. The aforementioned discussion seemed to point to 16-bit files when referring to TIFFs taken from S2 Pro image-capture, when 8-bit files are actually what is acceptable. (Or so I am led to believe.)

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