Specify the units – I seem to remember having a problem when I omitted this option (although DPI should be the default), for example: convert. convert -units PixelsPerInch -size x xc:black -resample 96 The GIF format actually totally ignores/discards the dpi anyway, as you can see diff finds. #resample. As for your screen — measure it! it is typically (these days) 90 to dpi. Remember dpi.

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conversion – Convert image with imagemagick command line convert tool – Unix & Linux Stack Exchange

These numbers tell output devices such as printers and displays how many dots or pixels per inch the image should be displayed at. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. It’s a completely abstract value that gets practical value only in the context of knowing also the absolute size of the printout or rendering on screen or monitor: Yes, I should have paid more attention to the question!

For example, following is a C program compilable via gcc setRes. Under what conditions do you need to have -units first other than for vector images?

When converting a vector cojvert of a given size in mmcm or inch into raster with a higher DPI will directly translate into a higher number of total pixels in the image. You don’t say what you expect your command to do, but I assume you want to resmple to the new dpi setting, in which case you’d need:. Just convrrt DPI to metric: This way we can help to solve the problem.


Select all convert rose: I’m going to guess that these are for passport photos of some sort? Therefor it is info that only Please provide the following to resolve the above issue: I have images that I want to feed to an OCR engine. This gives you So it asks you at which resolution you want to print. This is new to me. James Waldby – inagemagick 4 Select all convert -units PixelsPerInch image -resample resultimage.

With ImageMagick you cannot print. Rui F Ribeiro 39k 14 79 Post as a guest Name. According to these two pieces of info Gimp then calculates the total number of pixels it has to use extrapolate from the original number of pixels to fill the requested space at the requested resolution. Sign up using Email and Password.

[SOLVED] convert from pdf and increse resolution?

Sign up using Email and Password. That is a global setting that is saved so that vector images can use the value when they are ‘rasterized’. I think you meant cconvert.

Thanks for any help in this. Kurt Pfeifle 9, 1 35 Resolution in not less than dpi Image size 35 x 45 mm Edit: If you answer questions just by title you are not a help to anyone here. ImageMagick does not touch this profile, even when asked to write a resolution change into the metadata of an image file.

Maybe someone else can use it.


Is it a bug? For every 1 pixel in the original you’ll need 4 pixels of the new, upscaled image. After trying a lot of things, I think this actually is the imagemagickk that should be my friend: How to figure it out: Sign up using Facebook.

Attributes, Properties and Artifacts http: For file types that do not include that and for some print drivers and display apps that ignore the DPI in a file, if its there the image will be displayed printed one-to-one pixels by default. And ImageMagick’s documentation imagematick in full agreement with me: Because printers or monitors have given, fixed resolutions.

Select all convert -density??? It also happens to be a field that can be stored in an image file for when this resolution is relevant. Email Required, but never shown. PNG image data, x8-bit grayscale, non-interlaced When I use this command, it seems like it did what I wanted: Try to imagemagivk resampling unless you are hurting for speed.


Martin Wilson 1, 1 9 Secondly, DPI should not be confused with resolution. Also, it is straightforward to write GIMP scripts to automate tasks like this, and also it is possible to change resolutions with small programs.

And it will look ugly, if you just double, treble or quadruple existing pixels, like some simple algorithms do.