Handling CMYK Files as Separate Images

LEADTOOLS supports loading TIFF CMYK files without converting the data to BGR. This is done by loading each CMYK plane as a separate page in an Image and will be obtained by calling RasterCodecs.LoadCmykPlanes method. Alpha channel information will be loaded into the 5th page, if present in the input file. If the TIFF CMYK format doesn't include the source file, load the image normally by calling RasterCodecs.Load method, then obtain the CMYK planes by using ColorSeparateCommand.

To paint the planes, call RasterImagePainter.PaintCmykPlanes method.

To save the planes as TIFF CMYK, call RasterCodecs.SaveCmykPlanes method.

To save as another format, create a BGR Image using ColorMergeCommand or by calling RasterColorConverterEngine.ConvertCmykPlanes method, then save the image by calling RasterCodecs.Save method.

Conversion of CMYK to BGR

LEADTOOLS provides two methods to convert the CMYK input data to BGR:

Automatic Conversion

When loading a CMYK file by calling one of the load methods (RasterCodecs.Load or RasterCodecs.LoadAsync), the conversion will be performed automatically using CMYK profile if:

• The input file contains an embedded ICC CMYK profile, then the embedded profile will be used.
• The input file does not contain an ICC profile, then the default LEADTOOLS CMYK ICC profile will be used.

Custom Conversion

The conversion can be performed using custom CMYK ICC profile in the following manner:

1. Load the input file as CMYK planes by calling RasterCodecs.LoadCMYKPlanes method.
2. Create a CMYK->BGR color conversion object using the custom ICC profile by calling RasterColorConverterEngine.Start method.
3. Convert the CMYK planes to BGR using the color conversion object by calling RasterColorConverterEngine.ConvertCmykPlanes method. The example in the method shows how to apply the conversion.

NOTE

The Image can be manipulated by manipulating each plane independently. Some transformations should be performed to all planes, while others should be performed to a particular plane. Examples:
* Spatial transformation like flip, resize, rotate, etc. should be performed on all planes. Otherwise, unexpected results may occur.
* Other transformations should be done to a particular plane. For example:
K plane controls the amount of black ink. Changing the intensity of the K plane will darken or lighten the bitmap.
Changing the brightness of one of the other planes will change the color rather than the image brightness.

To have a better understanding of what is needed to achieve a particular result, this requires studying how the CMYK planes are combined to make the final image.