NeXT TIFF question

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5 total messages Started by David De Vorchik Thu, 23 Jul 1992 09:54

#209

Author: David De Vorchik
Date: Thu, 23 Jul 1992 09:54

17 lines
750 bytes

Hi,

We are currently trying to decode some TIFF files that originated on a NeXT
box.  These icons have a strange samples per pixel value (0x20002), we
assume this is something to do with masking of the image (as some of them
are icons).

Can someone please mail me the exact format used? 

Any help would be grately appreciated.

Thanks,

 -- david

Acorn Computers Limited, England.
ddv@acorn.co.uk

Re: NeXT TIFF question

#239

Author: Ali Ozer
Date: Sun, 26 Jul 1992 01:46

19 lines
1256 bytes

In article <17124@acorn.co.uk> David De Vorchik writes:
>We are currently trying to decode some TIFF files that originated on a NeXT
>box.  These icons have a strange samples per pixel value (0x20002), we
>assume this is something to do with masking of the image (as some of them
>are icons).

Bizarre. NeXTSTEP never generates TIFFs with that spp; spp is always 1, 2, 3,
or 4.  In fact, given that the SamplesPerPixel tag is a short, the value
you specify doesn't look right. If it were to be 2 (which seems likely), then
you probably have a grayscale image with alpha.

Images with alpha aren't too complicated; they just have an extra channel
holding the transparency information, and the actual image itself is
premultipled with alpha. The alpha is stored as the last channel of data.

NeXTSTEP 2.x denotes alpha with the private MATTE tag; NeXTSTEP 3.0 uses
the newly created standard ExtraSamples tag.

Ali, Ali_Ozer@NeXT.com

Re: NeXT TIFF question

#241

Author: Eric P. Scott
Date: Sun, 26 Jul 1992 06:05

8 lines
720 bytes

In article <4481@rosie.NeXT.COM> aozer@next.com (Ali Ozer) writes:
>NeXTSTEP 2.x denotes alpha with the private MATTE tag; NeXTSTEP 3.0 uses
>the newly created standard ExtraSamples tag.

You mean alpha tiff format changed *again*???  [Before 2.0 NeXT
used PhotoMetricInterpretation=5.]  Arrgh!!!

					-=EPS=-

Re: NeXT TIFF question

#245

Author: Ali Ozer
Date: Sun, 26 Jul 1992 21:23

21 lines
1255 bytes

In article <1992Jul26.060536.22698@csus.edu> eps@cs.sfsu.edu writes:
>In article <4481@rosie.NeXT.COM> aozer@next.com (Ali Ozer) writes:
>>NeXTSTEP 2.x denotes alpha with the private MATTE tag; NeXTSTEP 3.0 uses
>>the newly created standard ExtraSamples tag.
>
>You mean alpha tiff format changed *again*???  [Before 2.0 NeXT
>used PhotoMetricInterpretation=5.]  Arrgh!!!
>
>					-=EPS=-

But Eric, what's the problem?  Our 3.0 images (with alpha) load under
2.0 just fine, and that was certainly the biggest concern...

Our 1.0 alpha format was real crufty. 2.0 fixed that by using a
private tag registered by SGI and used by Sam Leffler's library. As far
as I know, no one but SGI and NeXT used that format. The TIFF 6.0 spec
(just recently finalized) adopted a standard for alpha that was different 
and in NeXTSTEP 3.0 we decided to follow that.

Ali
Ali_Ozer@NeXT.com

Re: NeXT TIFF question

#270

Author: Eric P. Scott
Date: Tue, 28 Jul 1992 05:21

10 lines
918 bytes

In article <4482@rosie.NeXT.COM> aozer@next.com (Ali Ozer) writes:
>But Eric, what's the problem?  Our 3.0 images (with alpha) load under
>2.0 just fine, and that was certainly the biggest concern...

(1) Old files, and hence old formats, live forever.
(2) *My* biggest concern is being able to read NeXT-generated
    TIFF files w/o the AppKit (for example, on other
    platforms...).

					-=EPS=-

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