I have a related question. The various image file formats have their
own options and settings (compression levels, color space,
interlacing, etc.); is there a generic way to access these from within
my application?
For those who still remember BeOS (where the grass was green and the
girls were pretty), there was a concept called "Translators" (which
BeOS, in turn, borrowed from the Amiga). Each Translator was
basically an Image I/O codec, but you could also query them for a
"configuration view" which you could simply show in your own
application. That way, the app doesn't have to know the ins and outs
of all the file formats.
Does something like this exist on MacOS or do I have to create these
settings views myself?
Regards,
Sander
Actually, that occurred under 10.5 as well - what happens is that some
operations, it would seem those involving Core Image, cause the
internal representation to go to RGBA. Which is fine, but there
doesn't seem to be a way to write a plain RGB format TIFF. I had to
incorporate a third-party TIFF module to do that, as RGBA TIFF files
aren't very compatible with anything other than Apple.
Sandy
On Oct 12, 2009, at 5:07 PM, Ken Ferry wrote:
On Mon, Oct 12, 2009 at 4:36 AM, Peter C <[email protected]>
wrote:
I just stumble into a feature (or a bug ?), NSImage
TIFFRepresentation
produce RGB TIFF with a layer (when open under Photoshop).
Previously it
produce plain RGB TIFF under OS 10.5 and below. This cause some
part of my
programs interpret wrong RGB data, expecting 3 bytes instead of 4
bytes for
a RGB pixel. There is no mention in the documents about this
"feature".
Is there a way to restore the previous behavior of
TIFFRepresentation ?
You can look at CGImageDestination to get more options, but I don't
think
there's anything that provides control at that level.
In many cases there _must_ be data munging between the in memory
pixel
format and the on-disk file format. The precise munging is not
defined on
either input or output.
That is, don't make pixel format assumptions. The AppKit release
notes<http://developer.apple.com/mac/library/releasenotes/Cocoa/AppKit.html
discuss
how to avoid making pixel format assumptions in the section
"NSBitmapImageRep: CoreGraphics impedence matching and performance
notes".
-Ken
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