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Topic: CMYK and LibJpeg
Conf: (P-PDF) Developers, Msg: 86958
From: Las
Date: 5/2/2003 09:34 PM

Hi all,

This is the place where I am getting help to move in to right direction. So I am back here again. Hope somebody can help me. Here is the problem:

I am using LibJpeg for compressing image data read from a pdf file. It works fine with GreyScale and RGB images. But my approach is not working with CMYK images. All the images I am trying here are DCTDecoded with attribute flag value 1. Here is a code snippet from my compression function.

switch(clrSpace)
{
case 341: //ICCBased
cinfo.in_color_space = JCS_RGB;
break;
case 255: //DeviceGray
cinfo.in_color_space = JCS_GRAYSCALE;
break;
case 257: //DeviceCMYK
cinfo.in_color_space = JCS_CMYK;
break;
default: // assuming DeviceRGB for the time being, need to handle all the remaining ones as well
cinfo.in_color_space = JCS_RGB;
}
cinfo.input_components = numComps;

jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, quality, TRUE);
jpeg_start_compress(&cinfo, TRUE);

/* JSAMPLEs per row in image_buffer */
switch(clrSpace)
{
case 341: //ICCBased
row_stride = m_iWidth * 3;
break;
case 255: //DeviceGray
row_stride = m_iWidth * 1;
break;
case 257: //DeviceCMYK
row_stride = m_iWidth * 4;
break;
default: // assume RGB for the time being, need to handle all the remaining ones as well
row_stride = m_iWidth * 3;
}


Where clrSpace and numComps are read using PDEImageGetColorSpace,PDEColorSpaceGetName and PDEColorSpaceGetNumComps.

Is there anything else which needs to be addressed here?

Thanks
Las


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