[openbeos] Re: ShowImage "Mirror" Operations

Hi,

> I honestly don't know if the jpegs can be 100% losslessly
> rotated and written to disk. It's not a lossless format to begin with.

The original point of this discussion was that it *is* possible to rotate 
the JPEG in its encoded format, and that ShowImage should do just that.

> Most people don't care, I suppose, but it could start showing
> in the images, if an application lets you do lossy actions on them
> and you play with the same image one too many times.

I would assume that most people do care very much. Windows Fax and Image 
Viewer doesn't (didn't?) do it and it warns you about the fact. The result 
being that you're constantly paranoid about your precious fotos.... Like 
when you rotated the wrong direction (due to those sucky icons) and you 
have to rotate back twice - did you just reencode three times?!? :-)

One problem is going to be meta data, like EXIF info. This should not go 
away when ShowImage rotates the foto. One other extreme example would be 
rotating a Photoshop image. You would completely destroy your document if 
it contained anything else but a flat image. I think the solution to this 
problem is to make ShowImage rotate image data "in place" only if it 
*really* knows what it's doing. Otherwise it just writes the attribute. 
That way, we can special case the so commonly used JPEG and solve the 
original problem for most users without making a few others *really* angry.

Best regards,
-Stephan

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