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imagemagickimagemagick-convert
PKHunter
PKHunter

Reputation: 706

Simple ImageMagick real world usable

I've read the ImageMagick documentation here and here and been unable to achieve a couple of simple tasks. Would appreciate any simple pointers or direction, or even commands I can execute that will work on Linux.

  1. I want to convert any image-type (JPG, GIF, PNG, TIFF) to save to a PNG, losslessly, and as compressed as possible without any loss of quality. Ideally in 96 DPI so they look good in Retina screens.

  2. To then take the above generated PNG and also resize it in specific sizes, with height and width specified.

What am I missing with the convert command?

Upvotes: 0

Views: 100

Answers (1)

Mark Setchell
Mark Setchell

Reputation: 207818

If you want to convert a TIF, GIF or JPEG to PNG, the command is:

convert image.tif result.png

or

convert image.jpg result.png

In answer to your questions...

Question 1

PNG is lossless by definition, so that is not an issue. To get better compression of a PNG, you generally need to reduce the colours, i.e.

convert image.jpg -colors 64 result.png   # or try 255 which allows a palettised image

The dpi is pretty irrelevant until you print on paper. More pixels are needed if you want more quality on screen.

Question 2

If you want to resize an image without destroying its aspect ratio, use

convert image.jpg -resize 200x100 result.png   # retain aspect ratio

If you don't care if that makes the image look stretched or distorted, and you want exactly 200x100, tell ImageMagick that you really mean it by shouting:

convert image.jpg -resize 200x100! result.png  # ignore aspect ratio

Upvotes: 1

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