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Comparing two images
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Comparing two images


  • Subject: Comparing two images
  • From: Lorenzo <email@hidden>
  • Date: Fri, 28 Nov 2003 11:25:28 +0100

Hi List,
I have to compare two images (I mean byte by byte) and say whether they are
equal or not. Of course the first thing I do is to compare the fileSize.
If the fileSize are equal, I compare the imageSize, the resolution, the
depth... using the QT routines. They are fast.

If still equal I have to read byte by byte... If the files are very big e.g.
3GB, I suppose that I have to read and compare the files "chunk by chunk".
I mean the whole files, not only the Image Description Handles. Correct?

When I met the first different byte I close the routine and say: they are
not equal. Correct?

I have some Carbon code somewhere that opens files and read them chunk by
chunk using FSpOpenRF, GetEOF, SetFPos, FSRead. Do you think it can still
work well on MacOS X? I know they cannot manage data or resource forks >
2GB. Or, how to do that with Cocoa? With NSFileWrapper?

Thank you.

Best Regards
--
Lorenzo
email: email@hidden
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