Resizing images quickly?

BaltikaTroika · 10-11-2004, 04:59 PM

Is there any batch image resizing program out there for Linux? I've got a ton of high res photos from my digital camera I want to send via email, but don't really want to go in and do it all by hand for each one.

Thanks for any info,
Baltika

Dave Kelly · 10-11-2004, 05:11 PM

Change to the directory where the jpegs reside and run this script.

for i in *jpg; do echo $i; convert -size 320x240 $i -resize 320x240 $i; done

I use it for images in HTML code. Change the 320x240 to whatever you want.

stonecrest · 10-11-2004, 05:27 PM

Wow, I was wondering the same thing. Thanks for the tip, Dave!

One question though.. is there a way to specify a height and have the width adjusted based on the aspect ratio of the pictures? I would basically like images of various sizes to end up with a height of 50 pixels and a width of whatever it takes to keep the aspect ratio constant.

Dave Kelly · 10-11-2004, 06:55 PM

I don't have an answer to your question because I have never ask myself that question. I remember that HTML code will allow you to use only one dimension and auto-size the other.

Have you tested yet to see if what you ask will work?

If one has a lot of images to process they should learn ImageMagick and its many applications. Then learn enough 'bash scripting' ( for i in *.jpg; do echo $i; ???whatever???; done ) to step through a list of images.

Forezt · 10-17-2004, 05:39 PM

I'm trying to resize a batch of photos with that script, but the file names have spaces in them, so I always get this error:

Let's say I'm trying to resize a photo called "China 6 001.jpg".

It will say "convert: Unable to open file (6)."

Is there a way that I can make this script ignore spaces or something?

Dave Kelly · 10-17-2004, 06:35 PM

Eye (i) contains the name of your image. Try resizing that.

Please read the several manuals for the ImageMagick suite.
animate, display, identify, import, montage, mogrify, composit , convert, etc

And google search for a copy of this:

abs-guide-2.6.orig

Excellent tutoral on bash scripting.

Also please post the exact script you used that recieved the error.

Dave

Forezt · 10-17-2004, 07:27 PM

This is the exact script I used:

for i in "*.jpg"; do echo $i; convert -size 600x450 $i -resize 600x450 $i; done

Dave Kelly · 10-17-2004, 11:55 PM

Hmmm! What prompted you to enclose *.jpg in quotation marks?

Forezt · 10-18-2004, 05:10 PM

erm.... Whoops.

Actually, I tried it without them and it still give the same thing.

wapcaplet · 10-18-2004, 06:09 PM

To deal with those pesky spaces in the filenames (and to get that 50-pixel-height limitation you want), try this:

Code:

for i in *.jpg; do echo "$i"; convert "$i" -resize x50 "$i"; done

Note the quotation marks around the $i - that groups the filename into one piece so your shell doesn't think it's several separate arguments. AFAIK, you don't need the "-size" option for most images; only those in some kind of raw format that the program is unable to figure out a size for. The use of x50 tells convert to resize to 50 pixels in height, and scale the width accordingly.

Dave Kelly · 10-18-2004, 06:55 PM

Wapcaplets illustration works just fine.

Another question you ask was what to do about the spaces in the file name. In the tutoral on bash scripting is an illustration of changing the spaces to under-scores.

Also the following script renames files with spaces in the title.

Code:

#!/bin/bash
##take a command line parameter for a new file name.
##all images will have the same name and be numbered.
pname=$1
number=0
ONE=1

for filename in *.jpg
do
        let "number += 1"
        mv "$filename" "$pname-$number.jpg"
done

if [ "$number" -eq "$ONE" ]                 # For correct grammar.
then
        echo "$number file renamed."
else
        echo "$number files renamed."
fi

To create file names with spaces use this: # changename 1stword" "2ndword
To create file names without space use this: #changename filename

Forezt · 10-23-2004, 05:04 PM

Thanks ALOT for these scripts!

They saved me alot of time. I was trying to resize about 1,500 pictures I had taken in China for my website's gallery, and this did the trick.

Dave Kelly · 10-23-2004, 05:41 PM

Would you allow us to view the pictures when they are published?