Hi,

I want use libjpeg and I found?pasjpeg package in fpc that contains jpeglib.pas unit but I coudnt find a working demo to know how load a jpeg file and show it.
Can anyone point me to a better direction?

Regards,
Ara

pasjpeg is very low-level. Why not use tfpimage ?
use the fpimage unit, see the example converter program.

Michael.

Unit jpeglib does not use libjpeg.

fpreadjpeg, which is using fpimage, is an example for loading a jpeg using jpeglib.
And this in turn is used by the LCL.
So, a short LCL example loading and showing a jpeg using jpeglib is:

Put a TImage onto the form and add to FormCreate:

  Image1.Picture.LoadFromFile('example.jpg');

Mattias

Thanks but I need libjpeg using because of speed and fpimage with UsePalette := False is not fast enough.
My tests with libjpeg.dll and this header[1] id much faster than fpimage (half the time) so I wanted to have a native way using pasjpeg instead of a dll.

Regards,
Ara

Links:

1. http://www.dev-center.de/header/libjpeg?cat=header&file=libjpeg

Hello Ara, my tests with libjpeg-*turbo* are even more promising.

The following comparison between LCL and libjpeg-*turbo* was made decompressing for about one minute a sequence of several 4000x3000 JPEG pictures. The results are expressed in "pictures per second" and prove that libjpeg-*turbo* is about 7-8 times faster than LCL: AMD E2-1800 1.70 GHz
*Turbo i386-win32*
LCLlibjpeg-turboRatio
0.32 2.46 7.69x
*Turbo x86_64-win64*
LCLlibjpeg-turboRatio
0.36 2.72 7.56xIntel Pentium N3520 2.16 GHz
*Turbo i386-win32*
LCLlibjpeg-turboRatio
0.41 3.06 7.46x
*Turbo x86_64-win64*
LCLlibjpeg-turboRatio
0.43 3.35 7.79xIntel Core i5-4300 2.50 GHz
*Turbo i386-win32*
LCLlibjpeg-turboRatio
1.01 8.41 8.33x
*Turbo x86_64-win64*
LCLlibjpeg-turboRatio
1.10 9.18 8.35x

Best regards,
Sandro Cumerlato

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Very interesting! Thanks for sharing, maybe I was wrong in implementation. Do you used any different header or implementation? Can you share it?

@All : Is there a way to use?libjpeg-*turbo *with Lazarus *without* using an external library like DLL?
Regards,
Ara

How did you compare ?

IE, whats the source ?

Marc

Hello Ara,
I've used the attached header conversion for turbojpeg 1.4.2.

It is incomplete, but quite usable.

Best regards,
Sandro Cumerlato

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Hello Marc,
images are preloaded into separated memory streams, the core part of the comparison is performed by a separated thread:

procedure TMyThread.Execute;
var
  jpegDecompressor: tjhandle;
  jpegWidth: cint;
  jpegHeight: cint;
  jpegSubsamp: cint;
begin
  while (not Terminated) do
  begin
    case FTest of
      1 : begin // LCL
        FPicture := TPicture.Create;
        Images[FIndex].Position:=0;
        FPicture.LoadFromStream(Images[FIndex]);
        if (not Terminated) then
          Synchronize(@ShowBitmap);
        FPicture.Free;
      end;
      2 : begin // libjpeg-turbo
        FPicture := TPicture.Create;
        FPicture.Bitmap.PixelFormat:=pf24bit;
        jpegDecompressor := tjInitDecompress();
        tjDecompressHeader2(jpegDecompressor, Images[FIndex].Memory,
Images[FIndex].Size, @jpegWidth, @jpegHeight, @jpegSubsamp);
        FPicture.Bitmap.SetSize(jpegWidth,jpegHeight);
        tjDecompress2(jpegDecompressor, Images[FIndex].Memory,
Images[FIndex].Size, FPicture.Bitmap.RawImage.Data, jpegWidth, 0,
jpegHeight, cint(TJPF_BGR), TJFLAG_FASTDCT);
        tjDestroy(jpegDecompressor);
        if (not Terminated) then
          Synchronize(@ShowBitmap);
        FPicture.Free;
      end;
    end;
    inc(FIndex);
    if (FIndex > high(Images)) then FIndex := low(Images);
  end;
end;

http://pasteboard.co/hlatrJG.png

Suggestions are welcome!

Sandro Cumerlato

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Thank you very much for sharing. Clean.
I looked into it and its questioning for me how it works? Implementations like I mentioned is not like it and documentations and even dlls in here
http://www.libjpeg-turbo.org/Documentation/OfficialBinaries?are not like that.

Can you explain more?

Regards,
Ara

Hello Ara,
I'm using mingw-w64/msys2 binaries:

http://repo.msys2.org/mingw/i686/mingw-w64-i686-libjpeg-turbo-1.4.2-2-any.pkg.tar.xz http://repo.msys2.org/mingw/x86_64/mingw-w64-x86_64-libjpeg-turbo-1.4.2-2-any.pkg.tar.xz

and libturbojpeg-0.dll included.

Best regards.

Sandro Cumerlato

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Thanks.
I will test it.
Is there any particular reason that you didnt use official release? Why there is much difference? It seems I miss something!

Regards,
Ara

Hello Ara,

Aradeonas wrote

Thanks. I will test it.

Is there any particular reason that you didnt use official release?

I find convenient to use prebuilt binaries from the mingw-w64/msys2 toolchain, especially when I have to use several libraries within the same project.

Why there is much difference? It seems I miss something!

From README-turbo.txt:

libjpeg-turbo includes two APIs that can be used to compress and decompress JPEG images:

TurboJPEG API: This API provides an easy-to-use interface for compressing and decompressing JPEG images in memory. It also provides some functionality
that would not be straightforward to achieve using the underlying libjpeg API, such as generating planar YUV images and performing multiple simultaneous lossless transforms on an image. The Java interface for libjpeg-turbo is written on top of the TurboJPEG API.

libjpeg API: This is the de facto industry-standard API for compressing and
decompressing JPEG images. It is more difficult to use than the TurboJPEG API but also more powerful. The libjpeg API implementation in libjpeg-turbo
is both API/ABI-compatible and mathematically compatible with libjpeg v6b. It can also optionally be configured to be API/ABI-compatible with libjpeg v7
and v8 (see below.)

There is no significant performance advantage to either API when both are used
to perform similar operations.

Regards, Ara

Turbo demo binaries for both win32 and win64 are available at: http://www.djmaster.com/freepascal/demos/turbo.php

Best regards,
Sandro Cumerlato
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Hi,

Thanks for explanation Sandro.
I checked your demo and even other demos and I can say they are interesting, I wish I had the source specially JPEG demo so I can check your results.

Regards,
Ara