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vania
Neurotic (0) Inmate
Newly admitted

From:
Insane since: Jun 2004

posted posted 06-12-2004 13:15

Do you know how to do this?
I have an image with 40 Mb, at 16 bits.
When I convert it to 8 bits I loose half the information and the image changes to 20 Mb.
Is it possible to convert the image to 8 bits, duplicating its image size and maintaining its information - 40 Mb.???????

poi
Paranoid (IV) Inmate

From: France
Insane since: Jun 2002

posted posted 06-12-2004 13:44

vania: Welcome.

Yes, of course it's possible, but it's useless.

Well, it's easy to convert a 16bits to 8bits and keep its file size. If your image is say : 1000 x 1000 x 16bit, convert it to 8bits, then you can either change its canvas to 1000 x 2000 or add 3 channels ( or 4 if your image is in CMYK ) to your image. And voilà you just wasted 20Mb.

More seriously, in 16bits each channel have a precision of 2 ^16 = 65536 tones, while in 8bits its 2 ^ 8 = 256 tones. Once you convert a 16bits picture to 8bits it's NORMAL that the file size is divided by 2 since you go from 2 bytes to 1 byte per channel.



(Edited by poi on 06-12-2004 13:57)

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