Use ffmpeg to resize image

Is it possible to resize an image using FFMPEG?

I have this so far:

ffmpeg. -i 1.jpg -vf scale=360:240 > 2.jpg

I get the error message that 'At least one output file must be specified'

Is it possible?

You can try this:

ffmpeg -i input.jpg -vf scale=320:240 output_320x240.png

I got this from source

Note: The scale filter can also automatically calculate a dimension while preserving the aspect ratio: scale=320:-1, or scale=-1:240

If you want to retain aspect ratio you can do -

./ffmpeg -i 1.jpg -vf scale="360:-1" 2.jpg

or if you want to resize based on input width and height, let's say half of input width and height you can do -

./ffmpeg -i 1.jpg -vf scale="iw/1:ih/2" 2.jpg

where

iw: input width
ih: input height

It is also possible to resize an image to fit inside some dimensions and letterbox the rest.

Example command:

ffmpeg -i IN.png -vf "scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2" OUT.jpg

See this answer for more details.

Thanks to @andri-kurnia 's answer.

This example also shows how to resize multiple images (in windows):

for %j in (*.jpg) do ffmpeg -i "%j" -vf scale=480:-1 "Small-%~nj.jpg"

This command will resize all .jpg images in the folder, sets the width 480 while keeping ratio, and add "Small-" at the start of the resized image name. And I think for some types, it may be necessary to use -2 instead of -1. For specifying the height, we can use something like -1:480.

To reduce image scale to the bounding box of width:320px and height:240px.

ffmpeg -i src_image_path -vf 'scale=if(gte(a\,320/240)\,min(320\,iw)\,-2):if(gte(a\,320/240)\,-2\,min(240\,ih))' dst_image_path

a: aspect ratio
iw: in width
ih: in height

If the src image size is in the bounding box do no resize on it. If image has a big aspect ration than 320/240 and width is bigger then 320, resize width to 320 and keep the aspect ration. If image has a small aspect ration than 320/240 and height is bigger then 240, resize height to 240 and keep the aspect ration.