Alaska Software Inc. - Re: Problem saving PNG files on Windows XP
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AuthorTopic: Re: Problem saving PNG files on Windows XP
Andreas Gehrs-Pahl

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Re: Problem saving PNG files on Windows XP
on Mon, 02 Mar 2015 05:14:06 -0500
Thomas,

>> As JPG files (of screen shots) are considerably larger than PNG files
>Really? 
>That does not match with my experience at all.

PNG is 100% loss-less, as it uses zip compression, resulting in very clear 
graphics. Screen Shots -- meaning Dialog (Input) Screens -- that contain 
(relatively) large areas with a single color and other repetitive areas, 
are perfect for very good zip compression results.

If you have photos with random pixels and many different colors, JPGs will 
give you a much better result, as it is a (more or less) lossy compression 
that interpolates pixels and only saves some of them. JPGs using an 80% 
compression ratio will have pretty good quality, but will usually be 50% 
to 200% larger in size than a PNG file, if you save a dialog screen shot.

And if you have a black and white graphic (with just 2 bits for color), a 
GIF file will be usually smaller than either PNG or JPG.

Of course all of this is "usually" and "in general" and not an absolute. 
But in my experience, saving a screen shot of my application in PNG format 
will result in the smallest file, while giving the best picture quality, 
unless it is a screen shot that (just) shows a photo, of course.

Andreas

Andreas Gehrs-Pahl
Absolute Software, LLC

phone: (989) 723-9927
email: Andreas.GP@Charter.net
web:   http://www.Aerospace-History.net