Re: TIFFRepresentation, different TIFF format under Snow Leopard
Re: TIFFRepresentation, different TIFF format under Snow Leopard
- Subject: Re: TIFFRepresentation, different TIFF format under Snow Leopard
- From: Ken Ferry <email@hidden>
- Date: Tue, 13 Oct 2009 08:33:01 -0700
On Tue, Oct 13, 2009 at 12:39 AM, Paul M <email@hidden> wrote:
> Note especially this quote:
> "Adobe supports TIFF issues that directly relate to Adobe products. If a
> TIFF file is incompatible with an Adobe product ... our goal is to isolate
> and understand the problem so that it may be corrected in future releases"
> Taken from this page:
> http://kb2.adobe.com/cps/000/13da4f4.html
>
This hedge is probably in there because TIFF is designed to allow random
extensions. There's no hope of supporting anything anyone could possibly
put in a TIFF file.
However, hopefully a program won't put semantically necessary data in
private extensions unless the files aren't supposed to escape management by
that program.
That an Adobe product is so "Crappy" in this regard is surprising. I'm not
100% cretain, but I was under the impression that Adobe owns the Intelectual
Property that is the TIFF standard. They certainly support and foster it
to a high degree.
I agree. Of course one should file a bug with Adobe, but I would be
inclined to think that this problem was misdiagnosed. Lightroom really
ought to be able to read TIFF files with an alpha channel.
If there is indeed no api to do this, It would be reasonable to expect that
> the output format may be determined by the data comming in (to the image IO
> subsystem). If CoreImage is associating an alpha channel with the image,
> then try looking at CoreImage to either not add the alpha, or else to remove
> it prior to exporting your image.
> If you cannot do this with CoreImage, try looking at NSImage or other
> imaging components (Ken suggested CGImageDestination) to see if the alpha
> can be removed prior to writing it to disk. (Basicly, if you cant tell it
> not to write the alpha, try removing the alpha then write it out - then file
> an enhancement request!).
ImageIO (i.e. CGImageDestination) is the reading and writing framework used
by everything else. Please do file a bug, but please do understand: The
contract today is that ImageIO makes no promises about the relation between
in-memory pixel format and on-disk format on either reading or writing. You
need to code such that you don't depend on it, as discussed earlier in this
thread.
In particular, there has been talk of unilaterally standardizing everything
to ARGB when it's read in to simplify CoreGraphics and avoid future
conversions.
-Ken
Cocoa Frameworks
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