Solved

merging images - not exactly alphablending

Posted on 2004-09-19
4
154 Views
Last Modified: 2010-05-18

Delphi Graphics experts?

Suppose I have 4 or more images - let's make it 4 for simplicity, and assume they are of equal size. I want to "composite" these images - place them on a new image in the four quadrants (bottom left,bottom right, top left, top right) - in such a way that there is a "smooth transition" between them.

So, between the top left and top right, there should be no obvious boundary... it should "look like" elements of both images are present.

This gets more complex at the center, where there are 4 (in this simple case) adjacent images.

Has anyone done this? And got nice-looking results?

Code would be nice

0
Comment
Question by:Mutley2003
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
4 Comments
 
LVL 34

Accepted Solution

by:
Slick812 earned 500 total points
ID: 12106759
hello Mutley2003, you do not give very much info about the size of thr different aspects of your images, I have done Edge Blending for bitmaps before, although never more than Two bitmaps at a time, here is some code that tries to do a 4 bitmap blend, however, the math required for the center 4 bitmap blend, is not something I hve time now to figure out, I think it would require a 4 way matrix intered from a trigomometry distance from the center point, but this is more than I have time to try and figure out, , , , , ,

I do a 4 quadrent 3 bitmap blend for the center square, and it is not a perfect blend

code for a button click -


procedure TForm1.sbut_Blend4Bmpssbut_Blend4BmpsClick(Sender: TObject);
type
  Pbgra = ^Tbgra;
  Tbgra = packed record
    b, g, r, a: Byte;
    end;

  ParyBGRA = ^TaryBGRA;
  TaryBGRA = Array[Word] of Tbgra;

const
BlendWidth = 38;

var
ULBmp, URBmp, LLBmp, LRBmp, OutBmp: TBitmap;
BmpW, BmpH: Integer;
x, y: Integer;
pOne, pTwo, pOut: ParyBGRA;
BlendAmt,Blend1, Blend2: Single;
begin
BmpW := (PaintBox1.Width div 2);
BmpH := (PaintBox1.Height div 2);
ULBmp := TBitmap.Create;
ULBmp.LoadFromFile('E:\Blend11.bmp');
ULBmp.PixelFormat := pf32Bit;
URBmp := TBitmap.Create;
URBmp.LoadFromFile('E:\Blend12.bmp');
URBmp.PixelFormat := pf32Bit;
LLBmp := TBitmap.Create;
LLBmp.LoadFromFile('E:\Blend12.bmp');
LLBmp.PixelFormat := pf32Bit;
LRBmp := TBitmap.Create;
LRBmp.LoadFromFile('E:\Blend11.bmp');
LRBmp.PixelFormat := pf32Bit;
OutBmp := TBitmap.Create;
OutBmp.PixelFormat := pf32Bit;
try
  OutBmp.Canvas.Brush.Color := $EFFADF;
  ULBmp.Height := BmpH + BlendWidth;
  ULBmp.Width := BmpW + BlendWidth;
  URBmp.Height := BmpH + BlendWidth;
  URBmp.Width := BmpW + 1;
  LLBmp.Height := BmpH + 1;
  LLBmp.Width := BmpW + BlendWidth;
  LRBmp.Height := BmpH + 1;
  LRBmp.Width := BmpW + 1;
  OutBmp.Height := PaintBox1.Height;
  OutBmp.Width := PaintBox1.Width;

  BitBlt(OutBmp.Canvas.Handle,0,0, BmpW, BmpH, ULBmp.Canvas.Handle, 0,0, SRCCOPY);
  BitBlt(OutBmp.Canvas.Handle,BmpW+BlendWidth,0, BmpW, BmpH,
         URBmp.Canvas.Handle, BlendWidth,0, SRCCOPY);
  BitBlt(OutBmp.Canvas.Handle,0,BmpH+BlendWidth, BmpW, BmpH,
         LLBmp.Canvas.Handle, 0,BlendWidth, SRCCOPY);
  BitBlt(OutBmp.Canvas.Handle,BmpW+BlendWidth,BmpH+BlendWidth, BmpW,
         BmpH, LRBmp.Canvas.Handle, BlendWidth,BlendWidth, SRCCOPY);

  BlendAmt := 1.0 / BlendWidth;

  Blend1 := BlendAmt;
  for y := 0 to BlendWidth-1 do
    begin
    Blend2 := 1.0 - Blend1;
    pOne := ULBmp.ScanLine[y+BmpH];
    pTwo := LLBmp.ScanLine[y];
    pOut := OutBmp.ScanLine[y+BmpH];
    for x := 0 to ULBmp.Width -(BlendWidth+1) do
      begin
      pOut[x].r := ROUND((Blend2 * pOne[x].r) + (Blend1 * pTwo[x].r));
      pOut[x].g := ROUND((Blend2 * pOne[x].g) + (Blend1 * pTwo[x].g));
      pOut[x].b := ROUND((Blend2 * pOne[x].b) + (Blend1 * pTwo[x].b));
      end;
    Blend1 := Blend1 + BlendAmt;
    end;

  Blend1 := BlendAmt;
  for y := 0 to BlendWidth-1 do
    begin
    Blend2 := 1.0 - Blend1;
    pOne := URBmp.ScanLine[y+BmpH];
    pTwo := LRBmp.ScanLine[y];
    pOut := OutBmp.ScanLine[y+BmpH];
    for x := BlendWidth to ULBmp.Width - BlendWidth do
      begin
      pOut[x+BmpW].r := ROUND((Blend2 * pOne[x].r) + (Blend1 * pTwo[x].r));
      pOut[x+BmpW].g := ROUND((Blend2 * pOne[x].g) + (Blend1 * pTwo[x].g));
      pOut[x+BmpW].b := ROUND((Blend2 * pOne[x].b) + (Blend1 * pTwo[x].b));
      end;
    Blend1 := Blend1 + BlendAmt;
    end;

  Blend1 := BlendAmt;
  for x := 0 to BlendWidth-1 do
    begin
    Blend2 := 1.0 - Blend1;

    for y := 0 to ULBmp.Height - (BlendWidth div 2) do
      begin
      pOne := ULBmp.ScanLine[y];
      pTwo := URBmp.ScanLine[y];
      pOut := OutBmp.ScanLine[y];
      pOut[x+BmpW].r := ROUND((Blend2 * pOne[x+BmpW].r) + (Blend1 * pTwo[x].r));
      pOut[x+BmpW].g := ROUND((Blend2 * pOne[x+BmpW].g) + (Blend1 * pTwo[x].g));
      pOut[x+BmpW].b := ROUND((Blend2 * pOne[x+BmpW].b) + (Blend1 * pTwo[x].b));
      end;
    Blend1 := Blend1 + BlendAmt;
    end;

  Blend1 := BlendAmt;
  for x := 0 to BlendWidth-1 do
    begin
    Blend2 := 1.0 - Blend1;

    for y := (BlendWidth div 2)+1 to ULBmp.Height -BlendWidth do
      begin
      pOne := LLBmp.ScanLine[y];
      pTwo := LRBmp.ScanLine[y];
      pOut := OutBmp.ScanLine[y+(BmpH)];
      pOut[x+BmpW].r := ROUND((Blend2 * pOne[x+BmpW].r) + (Blend1 * pTwo[x].r));
      pOut[x+BmpW].g := ROUND((Blend2 * pOne[x+BmpW].g) + (Blend1 * pTwo[x].g));
      pOut[x+BmpW].b := ROUND((Blend2 * pOne[x+BmpW].b) + (Blend1 * pTwo[x].b));
      end;
    Blend1 := Blend1 + BlendAmt;
    end;

  // / / / / / / / / / / / / / / / / / / / / / / / / / / / /

  Blend1 := BlendAmt;
  for y := BmpH to ULBmp.Height -(BlendWidth div 2) do
    begin
    Blend2 := 1.0 - Blend1;
    pTwo := LLBmp.ScanLine[y-BmpH];
    pOut := OutBmp.ScanLine[y];
    for x := BmpW to ULBmp.Width - ((BlendWidth div 2)+1) do
      begin
      pOut[x].r := ROUND((Blend2 * pOut[x].r) + (Blend1 * pTwo[x].r));
      pOut[x].g := ROUND((Blend2 * pOut[x].g) + (Blend1 * pTwo[x].g));
      pOut[x].b := ROUND((Blend2 * pOut[x].b) + (Blend1 * pTwo[x].b));
      end;
    Blend1 := Blend1 + BlendAmt;
    end;
 

  Blend1 := BlendAmt;
  for y := BmpH to ULBmp.Height -(BlendWidth div 2) do
    begin
    Blend2 := 1.0 - Blend1;
    pTwo := LRBmp.ScanLine[y-BmpH];
    pOut := OutBmp.ScanLine[y];
    for x := BmpW + (BlendWidth div 2) to ULBmp.Width - 1 do
      begin
      pOut[x].r := ROUND((Blend2 * pOut[x].r) + (Blend1 * pTwo[x].r));
      pOut[x].g := ROUND((Blend2 * pOut[x].g) + (Blend1 * pTwo[x].g));
      pOut[x].b := ROUND((Blend2 * pOut[x].b) + (Blend1 * pTwo[x].b));
      end;
    Blend1 := Blend1 + BlendAmt;
    end;

  // / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /

  Blend1 := BlendAmt * (BlendWidth div 2);
  for y := BmpH +(BlendWidth div 2) to ULBmp.Height -1 do
    begin
    Blend2 := 1.0 - Blend1;
    pTwo := ULBmp.ScanLine[y];
    pOut := OutBmp.ScanLine[y];
    for x := BmpW to ULBmp.Width - ((BlendWidth div 2)+1) do
      begin
      pOut[x].r := ROUND((Blend1 * pOut[x].r) + (Blend2 * pTwo[x].r));
      pOut[x].g := ROUND((Blend1 * pOut[x].g) + (Blend2 * pTwo[x].g));
      pOut[x].b := ROUND((Blend1 * pOut[x].b) + (Blend2 * pTwo[x].b));
      end;
    Blend1 := Blend1 + BlendAmt;
    end;

  Blend1 := BlendAmt * (BlendWidth div 2);
  for y := BmpH +(BlendWidth div 2)+1 to ULBmp.Height -1 do
    begin
    Blend2 := 1.0 - Blend1;
    pTwo := URBmp.ScanLine[y];
    pOut := OutBmp.ScanLine[y];
    for x := BmpW + ((BlendWidth div 2)) to ULBmp.Width - 1 do
      begin
      pOut[x].r := ROUND((Blend1 * pOut[x].r) + (Blend2 * pTwo[x].r));
      pOut[x].g := ROUND((Blend1 * pOut[x].g) + (Blend2 * pTwo[x].g));
      pOut[x].b := ROUND((Blend1 * pOut[x].b) + (Blend2 * pTwo[x].b));
      end;
    Blend1 := Blend1 + BlendAmt;
    end;

  PaintBox1.Canvas.Draw(0,0, OutBmp);
  finally
  FreeAndNil(ULBmp);
  FreeAndNil(URBmp);
  FreeAndNil(LLBmp);
  FreeAndNil(LRBmp);
  FreeAndNil(OutBmp);
  end;
end;

 - - - - - - - - - - - - -  - - - - - - - - - - - - - - -  - - - - - - - -  - - - - - - -  - - - -

I hope this gives you some Ideas, and if you can come up with the math to calulate the relative blend values of 4 bitmaps, let me know
0
 

Author Comment

by:Mutley2003
ID: 12119034
Hi Slick

Thanks for the code.. as you say, the center is likely to be a problem. I have also been thinking as to how this might be generalized to more than 4 images, and possibly irregular. OK, this is just woolly thinking so far, but bear with me.

Suppose we have a "circle of compositing" of radius R.  This imaginary circle is passed over all the pixels in the output image and determines how the original (source) images contribute to the final image.  Assume each source image is positioned in its own invisible layer, and so these layers can overlap.

Approximate the circle by a polygon, so we can use polygon calculations .. point in polygon, polygon intersection etc.

For a given pixel in the final image

* which images does it directly map to (point in polygon)
* if only one image, then copy that source pixel
* if two or more, average those pixels

* are there any pixels in the source images within the circle of compositing ie within a radius R of this one. If so, allow them to make a contribution to this pixel with weight inversely proportional to the Euclidean distance between them. Note that this means that pixels which are not on a horizontal or vertical line can still influence the output pixel.

Well, it needs some more thinking I guess.



btw I will be out of the office for about a week, so don't take my lack of response for lack of interest.
0
 
LVL 34

Expert Comment

by:Slick812
ID: 12119544
OK, I read your last comment, but I can not say that I understood it, I can not get an Idea from your description, of any concievible final or output Image, I guess that there would only be a circle (or a polygon close to a circle) with some sort of "MIX" or blending of several images, which may not all be contained in the circle, or something? Anyway, I can not get a visual in my head of what this might look like, except that it is a circle. . . I do not see any edge blending to this.

And I can not place any of this with the original request of edge blending 4 images? ? ?
0
 

Author Comment

by:Mutley2003
ID: 12176743
Hi Slick812

I tried your code and it gives me good results. Ignore my post of 09/21/04

Thanks for the help
0

Featured Post

Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Creating an auto free TStringList The TStringList is a basic and frequently used object in Delphi. On many occasions, you may want to create a temporary list, process some items in the list and be done with the list. In such cases, you have to…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…

752 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question