=?ISO-8859-2?Q?pawe=B3_wola=F1ski?= on wrote...
| Hello!
| First I want to thank you Gabe Schaffer and Anthony Thyssen for help to
| choose proper Imagemagick's version.
|
| I've got another question. I'm working for website which converts
| thousands of pictures (about 40k) per day. We chose IM for managing of
| conversions. We noticed, that the most time is taken by resize of
| pictures. We made some test and:
|
| convert a.jpg -resize 200x b.jpg
| vs.
| convert -size 200x a.jpg -resize 200x b.jpg
|
| (notabene: a.jpg is a large picture)
| the second one is 10 times quicker than first. Could anyone explain that
| and using -size, please.
|
| Or.. what are possibilities for time optimizing for resize down pictures .
|
| Thank You in advance.
|
The -size is used to give a hint to the JPEG library as to how much of
the image data should be read from the image. the library will return
an image usally between the size given and that size with double the
dimensions, in your case it probably reads in an image 256x256 in size.
As this is much smaller, IM does not need to do as much processing to
correctly resize the image. It is equivelent to a 'pixel' filter resize
where lines and rows from the original image has been junked.
I recomend you make the hint at least twice as large as the final image
size so that Im at least has a good amount of data to generate a
reasonable result.
The -size setting is only used for JPEG format (and image creation).
For more info see IM examples
Reading JPEG Images
http://www.imagemagick.org/Usage/formats/#jpg_read
General Thumbnail Creation
http://www.imagemagick.org/Usage/thumbnails/#creation
Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]>
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