How can one count how many pixels a GIF image has via command line?

Question

I use Ubuntu. I have a large number of GIF images. How can one count how many pixels a GIF image has via command line?

Answer 1

You can use imagemagick package. Command like this will print the dimensions (in pixels) of a image:

identify -format '%w %h' example.gif

And the result will be (example):

128 1024

And as suggested in comment to calculate the number of pixels you can use command like:

identify -format '%W %H * + ' example.gif | dc -e0 -f- -ep

Answer 2

I eventually used this Python script to get the number of pixels in a GIF image:

from PIL import Image
image_path = 'random.gif'
img = Image.open(image_path)
total_pixels = 0
frame_count = 0

# Iterate through each frame in the GIF
try:
    while True:
        img.seek(frame_count)
        width, height = img.size
        total_pixels += width * height
        frame_count += 1
except EOFError:
    pass

print(f'Number of pixels in {image_path}: {total_pixels:,} pixels')

Example on https://i.sstatic.net/j7q3w.gif:

Number of pixels in j7q3w.gif: 96,738,345 pixels

Answer 3

You can also just use the file command on some image types, it works for .GIF and .PNG:

    # file myimage.gif
    # myimage.gif: GIF image data, version 89a, 1295 x 264

Multiplying the width by height (those last two numbers) gives the pixel count.

This could be automated with a pipe through awk:

    # file myimage.gif | awk '{print $NF * $(NF-2)}'   
    # 341880

To run over a bunch of files:

    # find . -iname \*.gif | while read filename; do pixels=$( file "${filename}" | awk '{print $NF * $(NF-2)}' ); echo "${filename}: ${pixels} pixels"; done

EDIT: Incorporate @Romeo Ninov's comment.

Answer 4

The final frame of an animated GIF can be addressed as animated.gif[-1] in ImageMagick. So you can get the width and height of the final frame using %W and %H and also the scene/frame number of that frame using %s - although this starts at zero. So the formula for total number of pixels is:

identify -format "%W * %H * (%s+1)\n" example.gif[-1] | bc
96738345

---

Or, maybe more simply with exiftool:

exiftool -p '$ImageWidth * $ImageHeight * $FrameCount' example.gif | bc
96738345

---

Another way... coalesce all the frames to their full size, convert to grey and a header-free stream of 1 byte/pixel, then count the bytes:

magick animated.gif -coalesce -depth 8 gray:- | wc -c
96738345

---

Another way... coalesce all the frames to their full size, append them all together and work out the product of width and height without calling any external utilities:

magick animated.gif -coalesce -append -format "%[fx:w*h]" -precision 10 info:
96738345