I guess this means that is doesn't have to be a 'perfect' picture with extreme resolution? Normally they say that a fine photo cannot be in GIF format, but I say that if you can settle with a normal good picture, then GIF is a really useful format, because GIFs are not "big", but IrfanView's GIF format gives a very high picture quality. Much higher than the nominal 256 colours. MUCH much higher!
In
IrfanView it is fantastic easy, because when you convert to GIF / save the image as GIF, IrfanView will ask you to click at any colour that should be made transparent (see attached screenshot). It is apparently also possible to make transparent areas in a PNG and JPeG, but I have never used these features.
If you install IrfanView (freeware)
http://www.irfanview.com/ you really MUST also install the free BAxBEx Shell Extension for IrfanView
http://www.baxbex.com/products.html (scroll ALL down). It is
sooo useful, when converting.
When converting into / saving as
GIF, in IrfanView, this box pops up:
>> Choose transparent color:
Click in the image to set the transparent color. Press ESC to ignore the transparent color. <<
Transparent colour chosen in a second with just one click!