Subject: Re: TIFF image file question

From: [email-masked] (Eric Gingold)
Date: Fri, 21 Jan 1994 16:52:19 GMT

Yong Lee IN/44 ([email-masked]) wrote:

> How can I psecify the tag paramters in TIFF file format for 12 bit or 16
> bit Black/White images? Also for RGB color images with more than 8 bit
> for each component?

According to the TIFF 6.0 specification, the "BitsPerSample" tag for
Grayscale or color  images (Tag #258) has only 2 allowable values:
4 and 8.  You could try to set the value to "12" or "16," but there is no
guarantee that your TIFF reader will interpret it correctly.  In fact, I
would wager that it would return an error.  The only commonly available
program I have seen that can handle 16-bit TIFF is NIH Image.

-- eric

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Eric Gingold, Department of Radiology, University of Alabama at Birmingham
    Birmingham, AL  35233    [email-masked]     (205) 934-3452   
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--------------------------------------------------------------------------
Eric Gingold, Department of Radiology, University of Alabama at Birmingham
    Birmingham, AL  35233    [email-masked]     (205) 934-3452   
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From: [email-masked] (Eric Gingold)
Date: Mon, 24 Jan 1994 14:53:31 GMT

I am posting the following for Greg Remington <[email-masked]>,
does not have posting capability:
_________________________________________________________________________

Date: 22 Jan 94 05:20:24 EST
From: Greg Remington <[email-masked]>
To: Eric Gingold <[email-masked]>
Cc: Yong Lee <[email-masked]>
Subject: 16 bit TIFF files

Eric,

I read, but cannot write usenet news and saw your reply to Yong Lee's
posting in sci.image.processing. I just wanted to add to the list of
programs that read gray-scale TIFF files where BitsPerSample is greater
than 8. Feel free to post the following reply if you feel it is
appropriate...

In <[email-masked]> [email-masked] (Eric Gingold) 

>program I have seen that can handle 16-bit TIFF is NIH Image.

I am the author of a family of programs that were written for PCs running
Windows which perform monochrome image acquisition, display, and processing 
functions. Because the original program was written to support scientific
grade  CCD cameras that deliver 12-16 bit monochrome data, the native pixel
data type is 16 bit integer. Most image processing and display functions use
the native format internally. I import 8 and 16 bit (both byte orders) TIFF 
images as defined by the BitsPerSample field.

I don't have the 6.0 TIFF specification, but the 5.0 specs do not restrict
the BitsPerSample field values and I do not believe that this is a correct 
interpretation of either standard. The 5.0 standard does define a number
of pre-defined formats (TIFF classes) which should be accepted by most
TIFF reader programs. This includes the G CLASS (gray scale) which does
restrict the values of BitsPerSample to 4 or 8. This shouldn't be
interpreted as a general restriction in the TIFF file format, but is
certainly an indication that many reader programs will not expect (but
should still respond appropriately) to other values of BitsPerSample.

If you or anybody else are interested in information about my 16 bit
image processing product family, contact me via email, fax, or
telephone.

Gregory K. Remington

eMail : [email-masked]
Fax   : +49 89 174070
Tel   : +49 89 173224

cc:Yong Lee