Set transparent background using ImageMagick and commandline prompt

Question

Suppose you have any image  PNG or JPG   This image has a white background and I need to make this background transparent   I have tried with these examples    convert original png -background none transparent png convert original png -background white -flatten -alpha off transparent png   but with no desirable results   How can I make it   IMPORTANT  Using convert command-line

User · Answer

Using ImageMagick  this is very similar to hackerb9 code and result  but is a little simpler command line  It does assume that the top left pixel is the background color  I just flood fill the background with transparency  then select the alpha channel and blur it and remove half of the blurred area using -level 50x100   Then turn back on all the channels and flatten it against the brown color   The -blur 0x1 -level 50x100  acts to antialias the boundaries of the alpha channel transparency  You can adjust the fuzz value  blur amount and the -level 50  value to change the degree of antialiasing   convert logo  -fuzz 25  -fill none -draw  matte 0 0 floodfill  -channel alpha -blur 0x1 -level 50x100   channel -background saddlebrown -flatten result jpg

User · Answer

I am using ImageMagick 6 6 9-7 on Ubuntu 12 04  What worked for me was the following   convert test png -transparent white transparent png   That changed all the white in the test png to transparent

User · Answer

This works for me   convert original png -fuzz 10  -transparent white transparent png   where the smaller the fuzz    the closer to true white or conversely  the larger the    the more variation from white is allowed to become transparent

User · Answer

Solution  color    convert filename png -format    pixel p 0 0    info -   convert filename png -alpha off -bordercolor  color -border 1           clone -fuzz 30  -fill none -floodfill  0 0  color          -alpha extract -geometry 200  -blur 0x0 5          -morphology erode square 1 -geometry 50           -compose CopyOpacity -composite -shave 1 outputfilename png   Explanation  This is rather a bit longer than the simple answers previously given  but it gives much better results   1  The quality is superior due to antialiased alpha  and  2  only the background is removed as opposed to a single color    Background  is defined as approximately the same color as the top left pixel  using a floodfill from the picture edges    Additionally  the alpha channel is also eroded by half a pixel to avoid halos  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   Comparison of results  Here is a comparison of the simple approach   -fuzz 2  -transparent white   versus my solution  when run on the ImageMagick logo  I ve flattened both transparent images onto a saddle brown background to make the differences apparent  click for originals       Notice how the Wizard s beard has disappeared in the simple approach  Compare the edges of the Wizard to see how antialiased alpha helps the figure blend smoothly into the background   Of course  I completely admit there are times when you may wish to use the simpler solution   For example  It s a heck of a lot easier to remember and if you re converting to GIF  you re limited to 1-bit alpha anyhow    mktrans shell script  Since it s unlikely you ll want to type this command repeatedly  I recommend wrapping it in a script  You can download a BASH shell script from github which performs my suggested solution  It can be run on multiple files in a directory and includes helpful comments in case you want to tweak things   bg removal script  By the way  ImageMagick actually comes with a script called  bg removal  which uses floodfill in a similar manner as my solution  However  the results are not great because it still uses 1-bit alpha  Also  the bg removal script runs slower and is a little bit trickier to use  it requires you to specify two different fuzz values   Here s an example of the output from bg removal

User · Answer

You can Use this to make the background transparent  convert test png -background rgba 0 0 0 0  test1 png   The above gives the prefect transparent background

User · Answer

Yep  Had this same problem too  Here s the command I ran and it worked perfectly  convert transparent-img1 png transparent-img2 png transparent-img3 png -channel Alpha favicon ico

User · Answer

If you want to control the level of transparency you can use rgba  where a is the alpha  0 for transparent and 1 for opaque  Make sure that final output file must have  png extension for transparency   convert    test png      -channel rgba      -matte      -fuzz 40       -fill  rgba 255 255 255 0 5        -opaque  rgb 255 255 255           semi transparent png

User · Answer

I had the same problem  In which i have to remove white background from jpg png image format using ImageMagick   What worked for me was   1  Convert image format to png  convert input jpg input png  2  convert input png -fuzz 2  -transparent white output png

[png] Set transparent background using ImageMagick and commandline prompt

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