Filter plug-in: How to mix my RGB image with source document image properly?

Question

Hi All,
My problem seems to be very common, but I can't find any answers in documentation.
I made Filter plug-in. It composes RGB image and mixes it with user source image in the document.
Now I load FilterRecord->
inData to byte array and recode each pixel with HostCSConvertColor function.
My code looks like that:
  byte 
*input = (byte*)filter_record->inData;
  int  
width = filter_record->inRect.right - filter_record->inRect.left; 
  int height = filter_record->inRect.bottom - filter_record->inRect.top;
  byte  
*transfer_buffer; 
  int size = width * height * 4; 
  transfer_buffer = new byte[size]; 
  byte *output = transfer_buffer;
  int  
planes = CSPlanesFromMode(fpb->imageMode, 3); 
  int16 color[4]; 
  for(j = 0; j < height; j++)  {
    for(i = 0; i < width; i++)    {
      for(k = 0; k < planes; k++)      {
        color[k] = input[i * align + k];      }
      HostCSConvertColor(filter_record->colorServices, space, plugIncolorServicesRGBSpace, color);      *
output = (byte)color[0]; output++;      *
output = (byte)color[1]; output++;      *
output = (byte)color[2]; output++;      *
output = 255; output++;    }
// for width
    input += line;
  } // for height
After that I mix my RGB image with output buffer and make back transition via
HostCSConvertColor to the document Color Space.It works very slow and looks ugly.
But I can't find any other way to mix my RGB image with photoshop image which can be not RGB Color Mode.
Your help will be very appreciated.
Sofia

Answer 1

Is it important to you to be able to process input color spaces other than RGB?
You can limit your filter to accept only RGB data if you set things up properly in the PiPL resource (e.g., yourfiltername.r file).
Here's an example for a filter that accepts only RGB or grayscale images:
SupportedModes
noBitmap,
doesSupportGrayScale,
noIndexedColor,
doesSupportRGBColor,
noCMYKColor,
noHSLColor,
noHSBColor,
noMultichannel,
noDuotone,
noLABColor
EnableInfo { "in (PSHOP_ImageMode, RGBMode, GrayScaleMode, RGB48Mode, Gray16Mode, RGB96Mode, Gray32Mode)" },
With the above, the filter will be disabled (grayed-out in the menu) for modes other than those listed.
-Noel