TBitmap32 to jpg (graphics32)

[Attila Kovacs 629]

How can I save the image from a TBitmap32 into a jpg (actually to the same type it was before loading, but let's start with jpg) without involving a TBitmap?

 

Edited August 18, 2022 by Attila Kovacs

[dummzeuch 1505]

You could try to use libjpeg-turbo (or even the original libjpeg, but I don't recommend it). I don't know how do use that with TBitmap32 though, I only used it with TBitmap and a BGR-in-memory-buffer. There are Delphi interface units for it.

[Attila Kovacs 629]

@dummzeuch Thx but I'm only interested in pure pascal solutions.

[dummzeuch 1505]

12 minutes ago, Attila Kovacs said:

@dummzeuch Thx but I'm only interested in pure pascal solutions.

I know of only one "pure pascal" solution for jpeg compression: nativejpeg

[Attila Kovacs 629]

I mean no extra dll's. This turbo lib depends on two dll's afaics.

[David Heffernan 2345]

I'm confused. The VCL ships with a JPEG encoder. 

[Attila Kovacs 629]

30 minutes ago, David Heffernan said:

I'm confused. The VCL ships with a JPEG encoder. 

Yeah, kinda, I don't know the internals, but that needs TBitmap which causes me gigabytes of unreleased RAM if I'm using it from threads.

I could not find any info on that either.

[angusj 126]

1 hour ago, Attila Kovacs said:

don't know the internals, but that needs TBitmap

Not necessarily. In my Image32 graphics library, I'm using Delphi's JPEG unit without touching TBitmap.

 

Edit: Sorry, the JPEG unit does use TBitmap.

Edited August 18, 2022 by angusj

[Attila Kovacs 629]

13 minutes ago, angusj said:

Not necessarily. In my Image32 graphics library, I'm using Delphi's JPEG unit without touching TBitmap.

Wow man, thank you for pointing this out, this is a remarkable library indeed, just what I was looking for.

The endless memory consumption of TBitmap is hereby solved.

[Attila Kovacs 629]

1 hour ago, angusj said:

Edit: Sorry, the JPEG unit does use TBitmap.

I see, still, something is different, memory is released asap.

 

With your lib, in 8 threads, converting 13GB/5200 jpg's the application takes 500MB-1GBPeak RAM.

With my converter, TPicture.LoadFromFile, DrawTo TBitmap, Resize to another TBitmap, assign to JPEGImage, save: RAM is linear up to 13GB+.

There is no memory leak, something in Windows is holding some working RAM or whatever. I don't care anymore. 

 

Edited August 18, 2022 by Attila Kovacs

[Anders Melander 1782]

6 hours ago, Attila Kovacs said:

How can I save the image from a TBitmap32 into a jpg (actually to the same type it was before loading, but let's start with jpg) without involving a TBitmap?

This one seems to do just that: https://github.com/taazz/simdesign/blob/87fdcc43f3a71016280cdbfc11de6cf4dd836254/simlib/nativejpg/NativeJpg32.pas

Haven't tried it though.

[angusj 126]

2 hours ago, Attila Kovacs said:

With your lib, in 8 threads, converting 13GB/5200 jpg's the application takes 500MB-1GBPeak RAM.

With my converter, TPicture.LoadFromFile, DrawTo TBitmap, Resize to another TBitmap, assign to JPEGImage, save: RAM is linear up to 13GB+.

There is no memory leak, something in Windows is holding some working RAM or whatever. I don't care anymore. 

Thanks, I'm very pleased to hear that. And I'm now curious as to how the performance compares with your converter?

Also, I could fairly easily modify Delphi's JPEG unit to expose the functions in the JPEG OBJ files and bypass TBitmap entirely but I'm not sure it's worth the effort thought it could improve performance .

[Attila Kovacs 629]

@Anders Melander Thanks, I'll check that too.

[Anders Melander 1782]

I just tried NativeJpg32, and while it has quite a few more dependencies (on the other SimDesign units) than what I would have liked, it worked well on everything I threw at it.

 

With regard to memory usage I tried loading a 16.4 Gb jpeg file (7900x5430 pixels) into a TBitmap32. The TBitmap32 as expected consumed 163 Mb. The peak overhead during load and conversion was 600 Mb.

Loading the same image as a BMP into TBitmap32 and then converting it to JPEG caused a peak overhead during conversion of 675 Mb and resulted in a jpg filesize of 11.1 Mb. Of course the two file were no longer identical due to the lossy jpeg encoding.

 

I did not experience any leaks.

[Clément 148]

Sorry if this is not related to your problem, but have you tried using TWICImage ?
 

[Attila Kovacs 629]

2 hours ago, Anders Melander said:

a few more dependencies ... than what I would have liked

Very PC. I lost my patience after the 3rd dependency, however, looking into the sources it is quality work indeed.

I'll check the speed against TImage32 when I found some time.

[Attila Kovacs 629]

2 hours ago, Clément said:

Sorry if this is not related to your problem, but have you tried using TWICImage ?

Never heard of it. Is it already in Berlin?

[Clément 148]

I'm using since Delphi XE

Should be in VCL.Graphics unit.

Edited August 19, 2022 by Clément

[David Heffernan 2345]

I'm not aware that the VCL jpeg unit leaks. How are you measuring that? 

[Attila Kovacs 629]

42 minutes ago, David Heffernan said:

I'm not aware that the VCL jpeg unit leaks. How are you measuring that? 

Who are you talking to?

Nobody said that it leaks, but somehow something won't release some memory until the app is closed, thus, it can not be used in a service.

Measure? ctrl-shift-escape, there you can measure. Or you can wait until the out of resources dialog.

[David Heffernan 2345]

8 minutes ago, Attila Kovacs said:

Or you can wait until the out of resources dialog.

That would be due to a leak.

 

Again though, I'm not aware that the VCL jpeg code leaks anything. Am I missing something? 

[Attila Kovacs 629]

1 minute ago, David Heffernan said:

That would be due to a leak.

 

Well, it's not my problem anymore. @angusj provided a solution to overcome that.

[David Heffernan 2345]

Most likely if there was a leak it was in your code, that would be my best guess. 

Edited August 20, 2022 by David Heffernan

[Attila Kovacs 629]

It's always your best guess and I don't have any other ideas either, but I don't know the internals and the Delphi manual is also very limited. 

Anyway, I can't invest any more time into this to figure it out myself and the solution I got I like much more as it skips an unnecessary step.

Edited August 20, 2022 by Attila Kovacs

[angusj 126]

18 minutes ago, Attila Kovacs said:

It's always your best guess.

In fairness, I think David asks a valid question. While it's certainly possible this presumed leak is due to a bug in Delphi code, based on probabilities it's much more likely in your code. Even though it's now working (without TJpegImage or whatever), it's likely still there, just not currently causing problems. If a short term fix is all you need then that's great. But it you're counting on this to work in a presumably unattended server long term, it's usually better to invest the time to find out the definitive cause now than have things blow up later when it's far less convenient.