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Reg -> RE: Cribtop goes on vacation and sees the Lexington II (8/21/2011 2:12:35 AM)
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quote:
ORIGINAL: Cribtop
Hmm, tried those as .gifs to minimize file size but not fully satisfied. Will try some modified .jpgs after dinner.
Hi Cribtop,
Looks like you had a great day.
The use of GIFs was a step in the right direction of reducing file size as the format faithfully reproduces images and tones but it is limited to only 256 colours. The world would be a dull place if we were limited to this number of colours. [:(] GIF format attempts to compensate by "dithering" (inserting patterns of pixels of the available colours) which in theory will give the closest match to the missing colours. This works if you view the picture from a distance but up close it is not so effective (notice how your pictures are all "grainy"). GIF format is best used on computer graphics with a limited number of colours.
This effect is made even worse with poor conversion tools. Your pictures only use 202 out of the 256 available colours so 20% of your limited colour range has been wasted so more dithering is required and the results aren't as good as they could have been!! I hope you didn't use MSPaint to do the conversion because it is the worst of the lot. Irfanview will use all 256 and intelligently pick the best colours to minimise dithering.
JPG format supports millions of colours and compresses the file size so it is the most suitable for a real world photographs (no dithering) and file size is smaller than any other format. However, it does this by introducing compression distortions into the image but for most photographs this effect is barely noticeable (unless the compression is turned up too high). This is why digital cameras use this format. Higher resolutions (larger images) also reduce the visibility of JPG distortions so that is why cameras are heading that way. I converted one of your pics to JPG and it was half the size of the original GIF.
The limitation of JPG is that it cannot handle high contrast (JPG has a real problem with Black & White checker board patterns which will always be blurry). You may have noticed the WITP screenshots which people have posted where you cannot read the red text. I get around this by using GIF format as it reproduces the coloured text faithfully (lossless is the technical term) and though there is dithering, I believe this is a small compromise for readable text. Another way of doing this is to use JPG with the compression turned way down (which sort of defeats the purpose of using JPG).
Sorry about being so long winded but I thought you might like to know why you didn't get the results you were expecting.
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