Small images on resize

Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
Post Reply
User avatar
anthony
Posts: 8883
Joined: 2004-05-31T19:27:03-07:00
Authentication code: 8675308
Location: Brisbane, Australia

Post by anthony »

You are using a legacy command line system that waw replaced with the introduction of ImageMagcik version 6.
See IM Examples Basics for details
http://www.cit.gu.edu.au/~anthony/graph ... k6/basics/

In summery... command line usage in versions before version 6 was ill-defined and broken, producing numerous odd and unexpected results.

You need to update you script to do...
convert in.jpg -resize 30% out.jpg

The -antialias is the default and does not effect the -resize operator. The -size is specific to JPEG format reading and can not be a percentage (it is probably the cause of your problem).

If you are trying to thumbnail to a specific known size then you can speed up JPEG reading
by adding a -size otpion BEFORE the JPEG filename.

I also recomend you use -thumbnail rather than -resize and it will also include a -strip to remove profiles, and do some scaling of very large images before using the -resize function to finish the job. This can improve performance.

For all the details on thumbnailing image using IM see IM Examples on Thumbnailsing.
http://www.cit.gu.edu.au/~anthony/graph ... humbnails/

If your thumbnail script has something to offer other IM users, please contribute to IM examples.
Anthony Thyssen -- Webmaster for ImageMagick Example Pages
https://imagemagick.org/Usage/
User avatar
anthony
Posts: 8883
Joined: 2004-05-31T19:27:03-07:00
Authentication code: 8675308
Location: Brisbane, Australia

Post by anthony »

I have a tendancy to just waffle on...

Please miss, can I leave, my brain is full!
Anthony Thyssen -- Webmaster for ImageMagick Example Pages
https://imagemagick.org/Usage/
User avatar
anthony
Posts: 8883
Joined: 2004-05-31T19:27:03-07:00
Authentication code: 8675308
Location: Brisbane, Australia

Post by anthony »

Those links are also my waffle :wink:

however I do like to add other peoples waffle to my waffle. Many additions and updates are from these forums.

yadda yadda yadda :)
Anthony Thyssen -- Webmaster for ImageMagick Example Pages
https://imagemagick.org/Usage/
Post Reply