Stretch the image canvas

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Which tools under Linux do you know that can stretch the image canvas? I need to stretch small images to a bigger unanimous dimension. How can I do that?

I meant to stretch the *canvas*, the image remains the same size. E.g, stretching a 300x300 image to 600x400, but the image stays intact, still 300x300 (and better in the middle of the image), but the canvas is stretched. So identify will returns 600x400, but the images looks the same.

Answer:

the best approach is to create the desired blank image, then

composite -gravity center odd_sized blank_image unanimous_sized

No distinction necessary, no calculation/awk needed.

Also check out:

Pad Out the Image
http://www.imagemagick.org/Usage/thumbnails/#pad

you can use a Viewport Crop, and flatten the result onto a background color.

convert -size 200x200 hatching.jpg -thumbnail '100x100>' \
        -gravity center  -crop 120x120+0+0\! \
        -background skyblue  -flatten    pad_view.gif

Another method to pad out an image is to overlay the thumbnail onto a background image (actual image, solid color or tile) that is the right size, in this case the 128x128 "granite:" built-in image.

convert -size 200x200 hatching.jpg -thumbnail '100x100>' \
        granite: +swap -gravity center -composite pad_compose.gif

Stretch the image canvas

convert -frame 400x600+0+0 -mattecolor white  infile outfile

Use -frame to set the desired size of the canvas. Set the bevel size to zero so you don't see them.

Use the mattecolor to force in the background color you want.

Dan Espen @telcordia.com

Stretch the image canvas

Hi, thank you all who have answered my question.

> See, the results are extraordinary big, not as supposed 520x130. why?

I solve it finally:

$ identify *.jpg
testimg.trim.jpg JPEG 98x130 DirectClass 8-bit 8497b 0.0u 0:01

$ convert -frame 520x130+0+0 -mattecolor white testimg.trim.jpg
testimg.new.jpg

$ convert -frame 211x0+0+0 -mattecolor white testimg.trim.jpg
testimg.new2.jpg

$ identify *.jpg
testimg.new.jpg[1] JPEG 1138x390=>569x195 DirectClass 8-bit 11723b 0.0u 0:01
testimg.new2.jpg[2] JPEG 520x130 DirectClass 8-bit 9091b 0.0u 0:01
testimg.trim.jpg[3] JPEG 98x130 DirectClass 8-bit 8497b 0.0u 0:01

See, now "new2" has the right size, whereas "new" not. The trick is that the "<width>x<height>" if for the *single border* size, not the finial output size.