SOLVED: Special effects
lazarus / 39-Graphics

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AsleyCruz · 2020-04-22 11:41

Good morning coders

Does anybody have any functions of how to apply special effects on
images?
Effects like grayscale, sepia, invert colors, brightness,
horizontal/vertical flip

Thanks in advance, guys.

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winni · 2020-04-22 12:11

hI1

Everything you asked for is built in the BGRAbitmap:

grayscale, grayscaleInPlace, negative, horizontalFlip, verticalFlip.

Brightness and Sepia I am not shure and now I have not Lazarus at
hand.

Winni

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winni · 2020-04-22 12:20

Hi!

Here  is the algorithm foe Sepia:

https://www.geeksforgeeks.org/image-procesing-java-set-6-colored-
image-sepia-image-conversion/

Winni

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circular · 2020-04-22 13:08

About Brightness you can use the Normalize function to use all
possible colors from black to white.

Otherwise you can simply multiply the values of each RGB channels or
add/substract a constant.

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lucamar · 2020-04-22 13:53

A good source for those (and lots more) kind of things was Earl F.
Glynn's Reference Library, most of which can be found at the Internet
Archive's Wayback Machine.

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winni · 2020-04-22 16:29

Hi!

Just implemented the missing Sepia.
The function Sepia () create  a copy of the TBGRAbitmap but in Sepia
color.


Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i function
range2byte (float: single) : byte; inline;beginif float > 255 then
float := 255 else   if float < 0 then float := 0;   result := round
(float);end; function toSepia (col : TBGRAPixel) : TBGRAPixel;
inline;beginresult.red :=   range2Byte (0.393*col.red +
0.769*col.green + 0.189*col.blue);result.green:= range2Byte
(0.349*col.red + 0.686*col.green + 0.168*col.blue);result.blue :=
 range2Byte (0.272*col.red + 0.534*col.green +
0.131*col.blue);result.alpha := col.alpha;end; function Sepia (Orig:
TBGRABitmap) : TBGRABitmap;var dest : TBGRABitmap;    i : Integer;   
p,q : PBGRAPixel; begindest := TBGRAbitmap.create (Orig.width,
Orig.height);p := Orig.Data;;q := dest.Data;for i := 0 to
Orig.NbPixels-1 do   begin   q^ := toSepia (p^);   inc(p);   inc(q); 
 end; // i dest.InvalidateBitmap; result := dest;end;                
     
Winni

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winni · 2020-04-22 17:33

Hi!

As test:

"Marianne" in Sepia.
Long llive the french revolution!

Winni

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AsleyCruz · 2020-04-22 17:59

Quote from: winni on April 22, 2020, 02:11:19 pmhI1

Everything you asked for is built in the BGRAbitmap:
grayscale, grayscaleInPlace, negative, horizontalFlip, verticalFlip.

Many thanks Winni,
I will check the functions out. I haven't used BGRAbitmap too much.

Great sample code with sepia... Thanks for your time.

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circular · 2020-04-22 22:33

yeah revolution! Well these days, not really able to go out though.

Channels are in sRGB colorspace, which has a gamma. If you want to do
transformations in linear RGB, first transform the value with
GammaExpansionTab and in the end back with GammaCompressionTab.

Using linear RGB will give you less dark areas.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i function
CompressF (float: single) : byte; inline;begin  if float > 65535 then
float := 65535 else   if float < 0 then float := 0;   result :=
GammaCompressionTab[round (float)];end; function toSepia (col :
TBGRAPixel) : TBGRAPixel; inline;begin  with GammaExpansion(col) do 
begin    result.red :=   CompressF (0.393*red + 0.769*green +
0.189*blue);    result.green:= CompressF (0.349*red + 0.686*green +
0.168*blue);    result.blue :=  CompressF (0.272*red + 0.534*green +
0.131*blue);  end;  result.alpha := col.alpha;end;

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winni · 2020-04-22 23:43

Quote from: lucamar on April 22, 2020, 03:53:12 pmA good source for
those (and lots more) kind of things was Earl F. Glynn's Reference
Library, most of which can be found at the Internet Archive's Wayback
Machine.

Thanx! I did not know that efg is reorganizing his pages.
A good source since decades!

Winni