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Long Bug with PNG pixilation

Publié : 13 nov. 2015 2:27
par naiden
Hello Team. From year / two / three, looong long time ago, I found some strange in my edited files. But didn't noticed carefully what is going, I just was in thinking that it is a little program with its little malfunction. Until two months ago when I found serious differences in original and output files. First I found pixilation in image objects which I am resizing from big to small. They all have transparent layers. And Yesterday I tried just to flip one small PNG image with size like icon which have transparent layer. The output format is pixelated! Then I tried to do the same with BMP file and found there is no problem.

I remember the same problem with another program called iConvert Icons. We reported to developer that we get serious pixilation even when extract images from EXE and DLL files, and sent him examples with different programs and different outputs and after month he fixed this. In changes you find the following info:
New - Support for extracting large icons from DLL and EXE files
:arrow: Bug fixes - The edges of some icons were pixelated when scaling down to smaller sizes.


You can ask him what was the problem. If you can't find it of course. :roll:

Re: Long Bug with PNG pixilation

Publié : 13 nov. 2015 9:05
par Antonio
sorry don't understand, can you post a sample ?

Re: Long Bug with PNG pixilation

Publié : 14 nov. 2015 11:14
par naiden
Antonio a écrit :sorry don't understand, can you post a sample ?
OK. Now I attempted to make export from PNG to BMP with many files, but there is no visible pixilation. No matter this we have good sample to make our test. As I said before I found these pixels very difficult during my editing with many layers. I noticed strange shadow for some of them.

Here is what you need:
Download the next image. Load it into FP and save as BMP. It will than pixelated.

Image

Here is result, FS is output from FastStone. :roll:
Image

Re: Long Bug with PNG pixilation

Publié : 14 nov. 2015 16:10
par Antonio
don't forget to display image at 100% because some time the pixilation is just in the display :wink:

Re: Long Bug with PNG pixilation

Publié : 14 nov. 2015 22:29
par naiden
Antonio a écrit :don't forget to display image at 100% because some time the pixilation is just in the display
I show you thumbnails. :!:
Did you explore first green image for test how program export? :?:

Re: Long Bug with PNG pixilation

Publié : 15 nov. 2015 9:46
par Antonio
In PhotoFiltre, BMP format don't support 32 bit with alpha channel. The alpha channel is ignored (it is a windows problem). if you save directelly in BMP format you lose the transparency edge.

It is better to ionsert a new background and merge.

In PFS or PF7 :

1. Open your PNG image
2. Insert new white background (menu Layer > Insert new background)
3. Merge all (menu Layer)
4. Now save as BMP 24 bit

Re: Long Bug with PNG pixilation

Publié : 15 nov. 2015 23:35
par naiden
Thanks a Lot Antonio.
Then is it possible for you to make the program automatically to add white layer when transparency is detected and user save as BMP or just always to adding, there is no point for transparency at all? Or it is difficult? Many programs are adding white background automatically for BMP formats.

Re: Long Bug with PNG pixilation

Publié : 16 nov. 2015 8:49
par Antonio
no because white is not allways the background color :cry:
I think it is better to set it manually.

Re: Long Bug with PNG pixilation

Publié : 16 nov. 2015 9:48
par naiden
Antonio a écrit :no because white is not allways the background color
If user set another color (he export merged layers) then it will be with another color no matter of additional 'white' background. The exported image haven't transparency and white can not be background, because it is behind and invisible. When user have transparency image for export, auto-background during export will be visible because is the only background. Hope you understand me a little. :(

Re: Long Bug with PNG pixilation

Publié : 16 nov. 2015 15:29
par Antonio
i understand your case but it is not global. For example, see this image :

http://img11.hostingpics.net/pics/539103Calque2.png

This image is alpha transparent but don't have uniforme background.
If you save it to BMP, you will see the original background but if i replace by white you loose it.
I understand in your case it is better, but in other case it is not better.

If you want to ignore alpha channel, juste use PhotoFiltre V6. PhotoFiltre 6 will automatically add white background because it don't support alpha channel. I think it is better in your case :wink:

Re: Long Bug with PNG pixilation

Publié : 16 nov. 2015 21:06
par naiden
Wow! Magic! :shock: I must to learn more. I understand you now. Can you recommend me some link with simple steps to make similar image? :roll:

Re: Long Bug with PNG pixilation

Publié : 17 nov. 2015 8:38
par Antonio
This image was posted here by fibi to signal an old bug :

viewtopic.php?f=2&t=21348&start=30

Some user create there own image with alpha channel using vectorial path and selection tool. I know there are some tutorials for this but don't remember exact link :oops: