From: Robert R. R. <rai...@gm...> - 2014-07-11 09:16:34
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Thank you all for the input. Very interesting aspects in your replies, although I do not know as much as you guys do on the technical part. Indeed, as some of you guessed, my main goal is to serve the tiles faster on the web. I thought that one of the things that need to be done is to reduce the size of the tiles. Because I also have satimages, I focused on jpeg at first. It works well for those (the size of the tiles is a lot smaller compared to png32 and png8); but then I tried obtaining smaller tiles using jpeg for the examples (not satimages) posted in the link. One of my main mistakes was that I compared jpeg size with both PNG32 and PNG8 (I thought I had PNG8 in all examples but as Glenn pointed out, there were two PNG32 files, my bad!) This made it clear that for those examples PNG8 is the way to go. Now, the question is if I can get these PNG8 tiles to get even smaller without loosing too much quality. I tried playing with the "quality" option of imagemagick which goes from 0 - 100. As I stated, the examples have a quality set to 90. I get the original image from Mapserver in a PNG32 format (great for overlays which have transparency but not so great for maps like in the examples that do not need transparency). Then I am able to use imagemagick on that image to crop/convert with some paramaters. My main issue is to find a good "receipt" for the tiles in the examples. As PNG32 provides a large number of colors, converting to png8 I guess that I limit them to 256. As I said, I need to preserve a good quality. A setback is that I do not know to analyze the image as you do in order to be able and obtain a good result. John's example of that image that contained a lot of pointless stuff is a good representation of what I lack. Best -- Raiz Roland Robert |