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Importing a PNG image degrades its quality.

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I am designing a GUI for a 7" high resolution LCD (1280x800), and it the GUI is designed for a purely touch interface.  I also want the icons to have a 3D somewhat realistic look to them.  This is a custom GUI, and these are not .ico files, but image files being used by the software to act as 'icon tools'.  o mock up the GUI for my programmers, I have been using PowerPoint.  I have created many of the icons in PP, either by scratch or, more often, by compositing images together.  I was showing the UI screens to the software engineers in PP format as well. 


Now I am at a point where we have been programming the UI in QT, and the programmers need actual image files (png format) to use in the code.  I find that on many of my icons require modification (removal of blemishes, edge blending, recoloring, etc, and I have relied on Paint.Net to accomplish these tasks.  What I have found, though, is that, when I export the files out of PP and into Paint.Net, the quality degrades signficantly, but they do not degrade nearly as much when I do the same maniuplations in PP.  Here are a couple of specific examples of what I have tried for comparison.


Take an image in PP, select it, Save it as a PNG file.  Import that PNG into Paint.Net.  For comparison, load the same PNG into PP.  The image in PP is better in image quality than it shows up in Paint.Net. 


Take a PNG image in PP and scale it down to 1/4 its size.  Zoom in and look at the quality.  Take the same PNG image into Paint.Net and Scale its size by 1/4.  Zoom in and look at the quality.  It looks signficantly worse in Paint.Net.  Is PP doing something different?


My programmer needs my PNG files in a 256x256 format.  I found that the size of the image on a PP page dictates its pixel size when exported as a PNG from within PP.  So I end up scaling the images (by trial and error) to a particular size, compositing them, then saving them as PNGs.  What I want to do is create the icons as layers in Paint.Net, scale the canvas to 256x256, and use the power of the tools there, then save them as PNG files.  However, when I do this, and then load them into PP, there is significant degradation in the image quality.


What I have had to do in order to use Paint.Net for this task and not lose too much in quality is to scale the images in PP to a large size, save them as PNG, import into Paint.Net, do my image processing (often using soften edges after surrounding the image with the color the icon will be sitting on in the UI, then deleting the background, exporting the image, importing it into PP, then scaling it down to the size I want, and Exporting as PNG.  For some reason, PP scales these images MUCH more cleanly than Paint.Net.


This is really confusing, because, in my mind, I should get much better results in Paint.Net than in PP, which is NOT designed for image editing.  Any suggestions would be very helpful.  I realize that I am a novice with Paint.Net, and all image processing programs, so I feel that I am missing something here.


Simple test.  Import PNG into Paint.Net.  Save as PNG.  The image quality degrades.  Should this really happen? 


I welcome any suggestions.  Please cc any comments to my work email (removed), since I do not often peruse this site.



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Simple test.  Import PNG into Paint.Net.  Save as PNG.  The image quality degrades.  Should this really happen? 

It isn't happening.  No really. The image quality does not degrade because the PNG format is a lossless one, no data is being lost during the save.


I suspect that what you're seeing is a difference in presentation.

Solution: Stop trying to use PP to create images when you know it's not designed for the task. Use an image editor like Paint.NET instead. Then you will be able to create, scale and save proper PNG files.

Also, I removed your email from your post. Spammers love you when to post your email address in an open forum ;)

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Seems like this may be an issue with how you're exporting from PowerPoint. PowerPoint is saving the images as viewed, not in actuality, so when you import to Paint.NET, it's smaller and worse quality, and when you put it back in to PowerPoint, it's worse than the original, as it's a smaller image. To prove this, export a PNG and then load it right back in to PowerPoint without using Paint.NET. You should still see that quality difference.

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