bashimagemagickwget
I'm trying to figure out a really fast method in bash of determining an images dimensions.
I know I could wget the image and then use imagemagick to determine the height and width of the image. I'm concerned that this may not be the fastest way of doing it.
I'm also concerned with having to install imagemagick when I only need a very small subset of functionality. I'm on an embedded system that has very limited resources (CPU, RAM, storage).
Any ideas?
Try something like this:
montage file1.jpg file2.jpg -geometry +0+0 -background none output.jpg
This will make the border between images as small as possible and whatever is there will be transparent.
To see a demo of the difference using builtin images, try these and compare:
$ montage rose: -resize 100x60 rose: -geometry +0+0 -background none montage.jpg
$ display montage.jpg &
$ montage rose: -resize 100x60 rose: montage.jpg
$ display montage.jpg &
See Montage Usage.
If you post an example of what you're getting and manually edit together an example of what you'd like as a result, we might be able to get a little closer to that.
Here are examples that I like better than the ones I originally posted above:
montage \( rose: -resize 100x46\! \) rose: -background gray montage.jpg
montage \( rose: -resize 100x46\! \) rose: -geometry +0+0 -background none montage.jpg
Nope, cat is surely the best way to do this. Why use python when there is a program already written in C for this purpose? However, you might want to consider using xargs in case the command line length exceeds ARG_MAX and you need more than one cat. Using GNU tools, this is equivalent to what you already have:
find . -maxdepth 1 -type f -name 'input_file*' -print0 |
sort -z |
xargs -0 cat -- >>out
Best Answer
As you note, you don't need the whole ImageMagick package. You just need
identify.You will also need the libraries the executable links to (and the libraries those libraries link to).
lddwill show a list. When I did this, it included some X libs, libjpeg, etc. and two libraries clearly from the ImageMagick package,libMagickCoreandlibMagickWand. Those look to be linked to the same bunch of things, so if you have that,identifyshould work.You don't have to download an entire image in order to get the dimensions, because these are in a header at the beginning of the file and that's what
identifylooks at. For example, here I'm copying the first 4 kB from a complete jpeg into a new file:4 kB should be more than enough to include the header -- I'm sure you could do it with 1/4 that amount. Now:
Those are the correct dimensions for
real.jpg. Notice, however, that the size (4.1KB) is the size of the truncated file, since that information is not from the image header.So: you only have to download the first kilobyte or so of each image.