BGRAbitmap Gradient

[Sanem]

Thank you for your remarks
Yes you were right about first and second remark, but when i set GammaCorrection to false the borders become dark, as you can see in screenshots(first one is with changing gtreflected to gtlinear and second one is with setting gamma correction to false).
thanks again

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs,
9.   BGRABitmap, BGRABitmapTypes, BGRAGradients, BGRAGradientScanner;
10.  
11. type
12.  
13.   { TForm1 }
14.  
15.   TForm1 = class(TForm)
16.     procedure FormCreate(Sender: TObject);
17.   private
18.     { private declarations }
19.   public
20.   end;
21.  
22. var
23.   Form1: TForm1;
24.  
25. implementation
26.  
27. {$R *.lfm}
28.  
29. { TForm1 }
30.  
31. procedure TForm1.FormCreate(Sender: TObject);
32. var
33.   g: TBGRAMultiGradient;
34.   gs: TBGRAGradientScanner;
35.   ArrBgraColor: array [0..2] of TBGRAPixel;
36.   bmpTemp: TBGRABitmap;
37.   pStart, pEnd: TPointF;
38.   w, h: integer;
39. begin
40.   w := 600;
41.   h := 360;
42.   //BGRASetGamma(2.3);
43.   //Invalidate;
44.   bmpTemp := TBGRABitmap.Create(w, h, clWhite);
45.   ArrBgraColor[0] := BGRA(255, 0, 0);//Red
46.   ArrBgraColor[1] := BGRA(0, 255, 0);//Green
47.   ArrBgraColor[2] := BGRA(0, 0, 255);//Blue
48.   g := TBGRAMultiGradient.Create(ArrBgraColor, [0, 0.49, 1], False, False);
49.   g.InterpolationFunction := @g.CosineInterpolation;
50.   pStart.x := 0;
51.   pStart.y := h div 2;
52.   pEnd.x := w;
53.   pEnd.y := h div 2;
54.   gs := TBGRAGradientScanner.Create(g, gtLinear, pStart, pEnd);
55.   bmpTemp.FillRect(0, 0, w, h, gs, dmSet, daFloydSteinberg);
56.   bmpTemp.BlendImage(0, 0, bmpTemp, boMultiply);
57.   bmpTemp.SaveToFile(
58.     'F:\simin\work\Lazarus\myProjects\(95-02-05)\TestGradient\Pics\pt5.png');
59.   //Invalidate;
60.   bmpTemp.Free;
61.   g.Free;
62.   gs.Free;
63. end;
64.  
65. end.
66.  

[circular]

Hmm... that's surprising. Here is what I get with different gamma corrections 0.4, 1.0 et 1.7:

[Sanem]

Hi,
My question is about point in photoshop gradient and bgrabitmap gradient, as you can see in screenshots, there is a concept in photoshop gradient between each position in gradient, which actually means that this position gain its color from color in 2 sides as 50 50, i wanted to ask is there a similar concept in bgra gradient?? it is not positions and colors directly! but i think i can make it with gradient point and and gaining average color of two sides, but i wanted first to know is there something similar in bgrabitmap or not.
thanks prior   

[circular]

There isn't this concept of where the 50/50 is in bgra gradient. I suppose indeed that adding an intermediate color would give you a similar result.
 

[SymbolicFrank]

When reading this discussion, I was wondering: why is the way Photoshop does something the only right way to do it?

[Sanem]

thank you circular, i will test it.

@SymbolicFrank, im developing something that designer designed in PS so i wanted to do exactly look like what PS do.

[Sanem]

Hi
for that "points in photoshop gradient" question I asked previously, i wanted to implement this concept in bgrabitmap and i have a new question about it, i read average methods in bgra doc but i couldnt find a similar method to gain that average color that i want, I thought maybe something like method below maybe give the answer, but in comparing with photoshop 50/50 color, as you can see in screen shots, it seems that there is an other way to gain 50/50 of 2 colors.
my method gain 0,127,127 for 50/50 of BGRA(0,255,0) and BGRA(0,0,255), the right 50/50 color of point in photoshop for same colors is (0,145,125) !
as you can see in screenshots

any help appreciate prior

Code: Pascal  [Select][+][-]

1. function TSixAm_form.GetAverageColor(C1, C2: TBGRAPixel): TBGRAPixel;
2. begin
3.   Result.red := round((c1.red + c2.red) div 2);
4.   Result.green := round((c1.green + c2.green) div 2);
5.   Result.blue := round((c1.blue + c2.blue) div 2);
6. end;
7.  

[circular]

Hmmm... Is it the same thing in Photoshop if the gradient start with yellow instead of red?

[Sanem]

I tested hsla to write that average function that i want, but the result I got is not what i want, i added my avg point as a new point in gradient and i did add its position as percent of colors, what i wnat is the exact color of this position(50% in my test) in the gradient, but i cant gain it with this formula!
as you can see in screen shots, i first got the result of gradient with 2 points(0 and 100) and second one is the result of same gradient with my point added exactly the point i mean (in my test 50%) with my avgcolor which i gained from hsla of each color.

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls,
9.   BGRABitmap, BGRABitmapTypes, BGRAGradients, BGRAGradientScanner;
10.  
11. type
12.  
13.   { TForm1 }
14.  
15.   TForm1 = class(TForm)
16.     procedure FormPaint(Sender: TObject);
17.   private
18.   public
19.     function AVGColor(c1, c2: TBGRAPixel; Percent: single): TBGRAPixel;
20.   end;
21.  
22. var
23.   Form1: TForm1;
24.  
25. implementation
26.  
27. {$R *.lfm}
28.  
29. { TForm1 }
30.  
31. procedure TForm1.FormPaint(Sender: TObject);
32. var
33.   bmp: TBGRABitmap;
34.   p1, p2: TPointF;
35.   g: TBGRAMultiGradient;
36.   gs: TBGRAGradientScanner;
37.   ArrBgraColor: array [0..2] of TBGRAPixel;
38.   //ArrBgraColor: array [0..1] of TBGRAPixel;
39. begin
40.   bmp := TBGRABitmap.Create(Width, Height);
41.   p1 := PointF(0, Height / 2);
42.   p2 := PointF(Width, Height / 2);
43.  
44.   //Way1
45.   //ArrBgraColor[0] := BGRABlack;
46.   //ArrBgraColor[1] := BGRAWhite;
47.   //g := TBGRAMultiGradient.Create(ArrBgraColor, [0, 1], True, False);
48.  
49.   //Way2
50.   ArrBgraColor[0] := BGRABlack;
51.   ArrBgraColor[1] := AVGColor(BGRABlack, BGRAWhite, 50);
52.   ArrBgraColor[2] := BGRAWhite;
53.   g := TBGRAMultiGradient.Create(ArrBgraColor, [0, 0.5, 1], True, False);
54.  
55.   g.InterpolationFunction := @g.CosineInterpolation;
56.   gs := TBGRAGradientScanner.Create(g, gtLinear, p1, p2);
57.   bmp.FillRect(0, 0, Width, Height, gs, dmDrawWithTransparency, daFloydSteinberg);
58.   bmp.SaveToFile('Pics\w2.png');
59.   bmp.Draw(Canvas, 0, 0);
60.   bmp.Free;
61. end;
62.  
63. function TForm1.AVGColor(c1, c2: TBGRAPixel; Percent: single): TBGRAPixel;
64. var
65.   h1, h2, Res: THSLAPixel;
66. begin
67.   h1 := BGRAToHSLA(c1);
68.   h2 := BGRAToHSLA(c2);
69.   with Res do
70.   begin
71.     hue := round((h1.hue + h2.hue) * Percent / 100);
72.     saturation := round((h1.saturation + h2.saturation) * Percent / 100);
73.     lightness := round((h1.lightness + h2.lightness) * Percent / 100);
74.     alpha := round((h1.alpha + h2.alpha) * Percent / 100);
75.   end;
76.   Result := HSLAToBGRA(Res);
77. end;
78.  
79. end.
80.  

[circular]

I am not sure you got my question so let me rephrase: what happens if you do a gradient with three colors (yellow, green, blue) with Photoshop? What intermediate colors do you have between green and blue?

[lainz]

Attached yellow, green and blue PS gradient.

[circular]

Thanks however I was thinking about yellow(ffff00)/green(00ff00)/blue(0000ff)

[lainz]

ok here it is

[circular]

Thanks!

Ok now the intermediate color is 008080.

So I deduce that Photoshop does a spline interpolation for each color channel separately.

[Sanem]

yes i think that in photoshop there is a difference between that exact point when the gradient start with red or yellow!