Набросал небольшой пример на Delphi. Ключевой момент
ExtraScanline.
program Project1;
{$APPTYPE CONSOLE}
uses
System.SysUtils,
System.Math,
Vcl.Imaging.PNGImage;
type
TRGB = record
r,g,b: single;
end;
TIMG = record
xmax, ymax: integer;
data: array of array of TRGB;
end;
function LoadPNG48(var img: TIMG; const fname: string): boolean;
var
png: TPNGImage;
x,y: integer;
scan,extra: pRGBLine;
begin
png:=TPNGImage.Create;
png.LoadFromFile(fname);
result:=png.Header.BitDepth=16;
if result then begin
img.xmax:=png.Width;
img.ymax:=png.Height;
SetLength(img.data, png.Height, png.Width);
for y:=0 to img.ymax-1 do begin
scan:=png.Scanline[y];
extra:=png.ExtraScanline[y];
for x:=0 to img.xmax-1 do begin
img.data[y,x].r:=(scan[x].rgbtRed shl 8 + extra[x].rgbtRed) / 65535;
img.data[y,x].g:=(scan[x].rgbtGreen shl 8 + extra[x].rgbtGreen) / 65535;
img.data[y,x].b:=(scan[x].rgbtBlue shl 8 + extra[x].rgbtBlue) / 65535;
end;
end;
end;
png.Free;
end;
procedure SavePNG24(var img: TIMG; const fname: string);
var
png: TPNGImage;
x,y: integer;
scan: pRGBLine;
begin
png:=TPNGImage.CreateBlank(COLOR_RGB, 8, img.xmax, img.ymax);
for y:=0 to img.ymax-1 do begin
scan:=png.Scanline[y];
for x:=0 to img.xmax-1 do begin
scan[x].rgbtRed:=round(img.data[y,x].r*255);
scan[x].rgbtGreen:=round(img.data[y,x].g*255);
scan[x].rgbtBlue:=round(img.data[y,x].b*255);
end;
end;
png.SaveToFile(fname);
end;
var
img: TIMG;
x,y: integer;
begin
if LoadPNG48(img, 'test48.png') then begin
for y:=0 to img.ymax-1 do begin
for x:=0 to img.xmax-1 do begin
img.data[y,x].r:=power(img.data[y,x].r, 1 / 2.2);
img.data[y,x].g:=power(img.data[y,x].g, 1 / 2.2);
img.data[y,x].b:=power(img.data[y,x].b, 1 / 2.2);
end;
end;
SavePNG24(img, 'test24.png');
end;
end.
