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 Tiff GrayScale		  New Topic  Reply to Topic
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izaque

Brazil
95 Posts
Posted - May 28 2012 :  12:31:22  Show Profile  Reply
In ImageEn manual says that "TIOTiff_Compression" ioTIFF_G4FAX Bilevel Group 4 CCITT compression, bidimensional. "Only black / white images," in the alpha channel.

What is the compression method for grayscale TIFF? ioTIFF_G4FAX?

fab

1310 Posts
Posted - May 28 2012 :  14:47:08  Show Profile  Reply
Gray scale is supported only with:
- ioTIFF_UNCOMPRESSED
- ioTIFF_LZW
- ioTIFF_JPEG
- ioTIFF_PACKBITS
- ioTIFF_ZIP
- ioTIFF_DEFLATE

As described in revision 6.0 of TIFF specification (except for ZIP and DEFLATE).
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izaque

Brazil
95 Posts
Posted - May 28 2012 :  16:22:34  Show Profile  Reply
I used the following code for compressing grayscale:

ImgMDigitalizar.MIO.Params [i]. BitsPerSample: = 8;
ImgMDigitalizar.MIO.Params [i]. Samplesperpixel: = 1;

ImgMDigitalizar.MIO.Params [i]. TIFF_Compression: = ioTIFF_JPEG;
ImgMDigitalizar.MIO.Params [i]. TIFF_JPEGColorSpace: = ioJPEG_GRAYLEV;

However the image is not compressed. Please, what's wrong?
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fab

1310 Posts
Posted - May 28 2012 :  22:28:23  Show Profile  Reply
For a bug on current version you should set SamplesPerPixel=3. Setting ioJPEG_GRAYLEV anyway ignore SamplesPerPixel (assuming 1).
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izaque

Brazil
95 Posts
Posted - May 29 2012 :  05:25:52  Show Profile  Reply
Thank you Fabrizio, now is working fine!
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