TImageEnProc.ConvertTo

Declaration

procedure ConvertTo(NumColors: Integer; DitherMethod: TIEDitherMethod = ieOrdered);
function ConvertTo(PixelFormat: TIEPixelFormat; PaletteType: TIEPaletteType = ieptMedianCut; DitherType: TIEDitherType = iedtSolid; CheckParametersOnly: boolean = false): boolean;
function ConvertTo(PixelFormat: TIEPixelFormat; Palette: array of TRGB; DitherType: TIEDitherType = iedtSolid; CheckParametersOnly: boolean = false): boolean; overload;

Description

First overload reduces the number of colors in the image.


When ieDithering is used and the required number of colors is <= 256 the resulting pixel format will be ie8p (unless LegacyBitmap is true or Location is ieTBitmap).

Second overload changes image pixel format using a combination of palette type and dithering algorithm when necessary.
This method may disable LegacyBitmap property if necessary.
Not all combinations of parameters are possible, check the return value. Returns True on success.

Third overload forces use of a specified palette.


Note:
◼If a palette is required, use ConvertToPalette
◼Any selection is ignored. The whole image is converted to the specified palette
◼A quantizer is used to reduce the number of colors using the method specified by ColorReductionAlgorithm

Demos

Method Testing

ImageEnView1.IO.LoadFromFile( 'D:\TestImage.jpg' );

  

// Convert to a 4-color ordered palette
ImageEnView1.Proc.ConvertTo( 4, ieOrdered );

  

// Convert to a 4-color dithered palette
ImageEnView1.Proc.ConvertTo( 4, ieDithering );

  

// Convert to a 16-color ordered palette
ImageEnView1.Proc.ConvertTo( 16, ieOrdered );

  

// Convert to a 16-color dithered palette
ImageEnView1.Proc.ConvertTo( 16, ieDithering );

  

// Convert to a 64-color ordered palette
ImageEnView1.Proc.ConvertTo( 64, ieOrdered );

  

// Convert to a 64-color dithered palette
ImageEnView1.Proc.ConvertTo( 64, ieDithering );

  

Examples

// Convert current image to 256 colors
ImageEnView1.Proc.ConvertTo(256);

// Convert current image to 461 (!) colors
ImageEnView1.Proc.ConvertTo(461);

// Convert current image to 16 colors, using Floyd-Steinberg dithering
ImageEnView1.Proc.ConvertTo(16, ieDithering);

// Convert pixel format to 256 colors with palette, using halftone palette and 8x8 dithering
ImageEnView1.Proc.ConvertTo(ie8p, ieptFixedHalftone256, iedtOrdered8x8);

// Convert pixel format to monochrome using halftone palette and 8x8 dithering
imageenview1.Proc.ConvertTo(ie1g, ieptFixedHalftone256, iedtOrdered8x8);



// Convert pixel format to monochrome with solid dithering
ImageEnView1.proc.ConvertTo(ie1g, ieptFixedBW, iedtSolid);

// Load a full-color image and save it as 256 color one
ImageEnView1.IO.LoadFromFile('D:\Im.jpg');
ImageEnView1.Proc.ConvertTo(ie8p, ieptFixedHalftone256, iedtOrdered8x8);
ImageEnView1.IO.Params.BitsPerSample := 8;
ImageEnView1.IO.Params.SamplesPerPixel := 1;
ImageEnView1.IO.SaveToFile('D:\Image256.bmp');

// Convert to 8 bits per pixel using the specified palette
const MYPALETTE: array [0..7] of TRGB = ((B: 0; G: 0; R:0), (B: 51; G: 0; R:0), (B: 102; G: 0; R:0), (B: 153; G: 0; R:0), (B: 204; G: 0; R:0), (B: 255; G: 0; R:0), (B: 0; G: 51; R:0), (B: 51; G: 51; R:0));
ImageEnView1.Proc.ConvertTo(ie8p, MYPALETTE, iedtErrorDiffusion);
ImageEnView1.IO.Params.BitsPerSample := 8;
ImageEnView1.IO.Params.SamplesPerPixel := 1;
ImageEnView1.IO.SaveToFile('output.png');

// Reduce image to colors within 216 color web palette (6 level RGB)
const
  Color_Steps: array[0..5] of byte = (0,51,102,153,204,255);
var
  Palette: array[0..215] OF TRGB;
  I: Cardinal;
  R,G,B: BYTE;
begin
  I := LOW(Palette);
  For R := 0 to 5 do
    For G := 0 to 5 do
      For B := 0 to 5 do
      begin
        Palette[ i ] := CreateRGB( Color_Steps[R], Color_Steps[G], Color_Steps[B]);
        Inc(I)
      end;
  ImageEnView1.Proc.ConvertTo(ie8p, Palette, iedtErrorDiffusion);
end;

See Also

◼ConvertToPalette
◼BitsPerSample
◼SamplesPerPixel

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