White border around png image after saving with IrfanView


Question

I created a simple circle drawing in Inkscape. Then I exported the drawing as png.

When I resize the image in IrfanView and save it as png then a thin white border appears around the circle.

You can see the difference between both images here:

Original image

Image after IrfanView

Why does saving with IrfanView put a white border around circle?

1
0
4/28/2012 2:14:00 PM

Accepted Answer

This is likely due to saving out a PNG-8 from IrfanView. PNG-8 has very basic transparency support, on or off. So with an anti-aliased edge like you have there, where you really need different levels of transparency, it is simply applying a transparency color map (taken from your white background color) and applying it to the pixels that aren't completely transparent.

To avoid this, make sure you are saving as a PNG-24.

3
4/28/2012 2:49:00 PM

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