CODEWITHSUNDEEP
imagemagickgraphicsmagick
user2650277
user2650277

Reputation: 6739

Converting images to a specific JPG quality

I want to convert image formats to JPG in a specific quality

The following command doesn't work for some reason , all i get is NULL

gm convert -quality 80 '/tmp/phpK31vNK' JPEG:'/tmp/phpK31vNK' && cat '/tmp/phpK31vNK'

However the following command works fine but graphicsmagick set the default quality which is 75

gm convert '/tmp/phpK31vNK' JPEG:'/tmp/phpK31vNK' && cat '/tmp/phpK31vNK'

Upvotes: 1

Views: 2307

Answers (2)

Mark Setchell
Mark Setchell

Reputation: 207465

If you don't need the output file after you have cated its contents, you can avoid creating it altogether as well as an unnecessary extra process to cat it. You just tell GraphicsMagick to create a JPEG and send it straight to stdout like this:

gm convert input.jpg -quality 80 jpeg:-

We can see it works by changing the quality and counting the bytes output like this:

# Low quality => small size
gm convert test.jpg -quality 60 jpeg:- | wc -c
9036

# Higher quality => larger size
gm convert test.jpg -quality 80 jpeg:- | wc -c
11513

Upvotes: 4

xenoid
xenoid

Reputation: 8869

Try:

gm convert image1 -quality 60 JPEG:image2

But if image1 is always a jpeg you can skip the JPEG: specification:

gm convert image1 -quality 60 image2

Upvotes: 5

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