Here's an example of the output from bg_removal. Requires you to specify two different fuzz values). Also, theīg_removal script runs slower and is a little bit trickier to use (it Results are not great because it still uses 1-bit alpha. Which uses floodfill in a similar manner as my solution. It can be run on multiple files in aĭirectory and includes helpful comments in case you want toīy the way, ImageMagick actually comes with a script called Since it's unlikely you'll want to type this command repeatedly, I Remember and if you're converting to GIF, you're limited to 1-bit (For example: It's a heck of a lot easier to It can be used to create, edit, compose, or convert bitmap images, and supports a wide range of file formats, including JPEG, PNG, GIF, TIFF, and PDF. Of course, I completely admit there are times when you may wish to use ImageMagick ® is a free, open-source software suite, used for editing and manipulating digital images. Notice how the Wizard's beard has disappeared in the simple approach.Ĭompare the edges of the Wizard to see how antialiased alpha helps theįigure blend smoothly into the background. White") versus my solution, when run on theīoth transparent images onto a saddle brown background to make theĭifferences apparent (click for originals). Here is a comparison of the simple approach ("-fuzz 2% -transparent Of course, ImageMagick's morphological operations don't (yet?) work at the subpixel level, so you can see I am blowing up the alpha channel to 200% before eroding. The same color as the top left pixel, using a floodfill from theĪdditionally, the alpha channel is also eroded by half a pixel to avoid halos. Writes a sequence of files named destination. ("Background" is defined as approximately magick convert source.psd -set dispose Background -coalesce destination.png. To antialiased alpha, and (2) only the background is removed as As you may have already noticed, there are actually subtle gradations (from black to white) of the 'black' lines in your example icon (likely due to anti-aliasing). which converts the whole image to transparency. 2 Answers Sorted by: 9 I want to change the white background to 3D94DB (Hex triplet notation) and change the black lines to white. The first image will replace the black background parts of the mask. Alpha Discrete treat the alpha channel independently. This is rather a bit longer than the simple answers previously given,īut it gives much better results: (1) The quality is superior due In Imagemagick 7, -alpha off will remove the alpha channel permanently such that -alpha on will not re-enable it. I'm running on windows with Version: ImageMagick 6.7.4-2 Q16. compose CopyOpacity -composite -shave 1 outputfilename.png Posts: 1 Joined: T01:13:56+01:00 Authentication code: 8675308 convert black background by sozin T01:23:12+01:00 Hello, I am stumped on what should be a very basic operation: converting a black background to a white background. morphology erode square:1 -geometry 50% \) \ alpha extract -geometry 200% -blur 0x0.5 \ \( +clone -fuzz 30% -fill none -floodfill +0+0 $color \ (Actually, threshold can be seen as an extreme case of using the color curves tool.Solution color=$( convert filename.png -format "%" info:- )Ĭonvert filename.png -alpha off -bordercolor $color -border 1 \ For finer control of the output, you can use tools like color curves, levels and contrast first to isolate the light and dark portions of the image better before thresholding. Since thresholding is often somewhat of a trial-and-error process to get a result you're happy with, particularly if the source image is not very close to black-and-white already, I recommend the GUI approach if possible, but if that is not an option for whatever reason you can do it through the command line as well. Running the above command on the example image produces the result shown below. You can use a graphical tool such as GIMP to do this interactively (you'll find the tool through the main menu -> Colors -> Threshold), or you can use ImageMagick something like this: convert colored.png -threshold 75% thres_colored.png Generally, you want to convert to grayscale first for more predictable results, but it is possible to threshold a full-color image as well. animation. png -append -scale 50 stacked.png animated gif from png files convert -delay 5 -loop 0. This results in a black-and-white image from an arbitrary input image. png -background black -resize 1024x768 -gravity center -extent 1024x768 fit.png mosaic with cropped images montage crop.jpg -geometry 460x460+0+0 mosaic.jpg scale and stack images convert. Basically, it takes an image as an input and outputs an image that has all pixels with a value below a given threshold set to black, and all pixels the value of which is above the threshold set to white. What you want is referred to as "threshold" in image processing.
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