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Friday, April 17, 2009

Technical Notes: Pierrot

Technical notes to myself: This latest postcard (Pierrot) gave me a better understanding of the various image processing problems I’ve been having:

1) Do not reduce the size of GIF files using Microsoft Paint (version 5.1). That causes subtle colored “stray pixels” to appear. Do the reduction in there to get the size in inches, but don’t save it. Then reduce it in PhotoPlus, by setting either the width or height to the desired inches value, and let it scale the other one accordingly. The result will be reduced to the size I wanted in Paint, but it will be clean. (The same problem might exist with BMP files.)

2) The “ghost affect” is still a problem and is probably due to the fact that JPG files use a lossy compression algorithm. I don’t think they are WYSIWYG when I’m processing them on a pixel by pixel basis. That’s why it’s not noticeable until I start to overlay images. (Except the clue that it’s there is if I do a test, and try to fill the image, there is a square edge all around the image, that doesn’t fill.) I need to look into what a JPG really is. I also might need to render it as a bitmap before I try to process it. (That might not be the right terminology, but I know what I mean, and I know what I need to look at to do that.)

3) When I “color” a black and white clip art picture, the first color I choose is most dominant, and ends up in places where I don’t want it. This occurs with clip art pictures that have a lot of different gray scale pixels in them. Using the “Black or White” choice as a processing first step might help with this problem, but I only tested it once, and not sufficiently enough to get meaningful test results.

3 comments:

indybev said...

Pierrot sent you on quite a journey! Thanks for sharing the information. Your card is lovely!

Ozstuff said...

Wow! Your colours are magnificent. Great postcard!

Buffy said...

Wow you really studied this one!You sound like me when I don't know something I google it and then go from there. Beautiful postcard.