'Declaration
 
Public Overloads Shared Sub ConvertColorSpace( _
   ByVal page As ImGearRasterPage, _
   ByVal newColorSpace As ImGearColorSpace, _
   ByVal backgroundColor As ImGearPixel _
) 

'Usage
 
Dim page As ImGearRasterPage
Dim newColorSpace As ImGearColorSpace
Dim backgroundColor As ImGearPixel
 
ImGearRasterProcessing.ConvertColorSpace(page, newColorSpace, backgroundColor)

public static void ConvertColorSpace( 
   ImGearRasterPage page,
   ImGearColorSpace newColorSpace,
   ImGearPixel backgroundColor
)

public: static void ConvertColorSpace( 
   ImGearRasterPage* page,
   ImGearColorSpace newColorSpace,
   ImGearPixel* backgroundColor
) 

public:
static void ConvertColorSpace( 
   ImGearRasterPage^ page,
   ImGearColorSpace newColorSpace,
   ImGearPixel^ backgroundColor
) 

Parameters

page

Image to change color space.

newColorSpace

New color space.

backgroundColor

Background to composite the image over when removing alpha channel.

If conversion removes the alpha channel from the image, the image is composited over a solid background specified by BackColor. Background should be in the same color space as the original image, but without the Alpha channel. For example, if the original image is in RGBA color space and newColorSpace is CMYK, background should have an RGB color space. The method will first transform the image into RGB and then to CMYK.

The following formula is used to burn alpha (i.e., to convert from RGBA/P to RGB):

If Page is not pre-multiplied:

I = I * A + B (1-A)

If Page is pre-multiplied:

I = I + B (1-A)

If the image contains extra channels, and newColorSpace contains extra channels, the method does not change them.

Note: Conversion to Grayscale colorspace takes into account human eye's sensitivity to different parts of the light spectrum. ImageGear uses the following formula when converting from RGB to Grayscale: Gray = Red * 77 / 255 + Green * 151 / 255 + Blue * 28 / 255. If you need to convert an image to Grayscale using equal weights for Red, Green and Blue, or any other weights, use ConvertColorSpace(ImGearRasterPage,ImGearColorSpace,Double[,])

Reference