[GDI +] how to convert a color image to a black/white image

When converting a color image to a black-and-white image, you need to calculate the valid brightness value of each pixel in the image.

Brightness values can be easily converted to black and white images.

The following formula can be used to calculate the valid brightness of a pixel:

Y = 0.3red + 0.59 green + 0.11 blue

Use color. fromargb (Y, Y, Y) to convert the calculated value.

ConversionCodeYou can use the following method:

[C #]

Public Bitmap converttograyscale (bitmap source)

{

Bitmap BM =   New Bitmap (source. Width, source. Height );

For ( Int Y = 0 ; Y < BM. height; y ++ )

{

For ( Int X = 0 ; X < BM. width; x ++ )

{

Color C = Source. getpixel (x, y );

Int Luma = ( Int ) (C. R * 0.3   + C. g * 0.59 + C. B * 0.11 );

BM. setpixel (X, Y, color. fromargb (Luma, Luma, Luma ));

}

}

Return BM;

}

 

 

[VB]

Public   Function converttograyscale () Function Converttograyscale ( Byval Source As Bitmap) As Bitmap

Dim BM As   New Bitmap (source. Width, source. Height)

Dim X

Dim Y

For Y = 0   To BM. Height

For X = 0   To BM. Width

Dim C As Color = Source. getpixel (x, y)

Dim Luma As   Integer   =   CINT (C. R * 0.3   + C. g * 0.59   + C. B * 0.11 )

BM. setpixel (X, Y, color. fromargb (Luma, Luma, Luma)

Next

Next

Return BM

End Function

Of course, this is a good method. You can also use the colormatrix class if you need to make color conversion easier. Next we will introduce

[To be continued...]