Legacy ImageMagick Discussions Archive

Hi all. This is my first post, thus please forgive my mistakes & my english. I need your helps with this situation:

I have a file with many points' coordinate. The file's content looks like this :

Code: Select all

color 1224,257 point color 1224,259 point color 1050,256 point color 1057,256 point color 1058,256 point...

And I want to use Windows' commandline to convert all the above points(pixels) of "X.png" to grayscale but keep those point's alpha transparent.
I hope I described the problem clearly, please ask me anything that can make it more understandable.
Really thanks for any help !
-----------------------------

Update: my file is "Pixel.txt" which contains fixed pixels' coordinates, and "X.png" can be ANY image. That I hope I can use it like this :

Code: Select all

convert  X.png  -colorspace gray -draw @Pixel.txt  X.png

But of course, that's not the correct way. I want to select all the pixel that have coordinates listed in "Pixel.txt" & convert them into graysacle, but leave the rest pixel as they are.

ImageMagick will not understand that text. To use ImageMagick, you need to change it to another format, such as "txt:". See http://www.imagemagick.org/Usage/files/#txt

For example, create a text file called "grays2.txt":

Code: Select all

# ImageMagick pixel enumeration: 2000,1000,255,srgba
1224,257: (128,128,128,0)
1224,259: (128,128,128,0)
1050,256: (128,128,128,0)
1057,256: (128,128,128,0)
1058,256: (128,128,128,0)

Then run this command:

Code: Select all

convert grays2.txt grays2.png

Now grays2.png will contain 5 pixels that are fully-transparent gray. All the other pixels are opaque white.

Thanks snibgo, but it seems that you misunderstood my question.
Please read my updated question. Thanks again.

see http://www.imagemagick.org/Usage/draw/#primitives

I do not know if -draw will read a file, but I think you can make a string variable

string="point x,y point x,y point x,y ... "

Then

convert image -fill gray -draw "$string" resultimage

Could you help me please?
I'm not going to fill the point x,y with gray, but going to CONVERT POINT X,Y TO GRAYSCALE.
Maybe not this :

fmw42 wrote:convert image -fill gray -draw "$string" resultimage

But something like this :

Code: Select all

convert image -toGrayScale "$string" resultimage

Thanks a lot !

"-draw" will read a file, using "-draw @something.txt", but the OP wants something else. I think the aim is to take an existing image and convert some of the pixels to greyscale. Something like ...

Code: Select all

convert ^
  X.png ^
  ( +clone -modulate 100,0,100 mask.txt -compose CopyOpacity -composite -channel Alpha -negate ) ^
  -compose Over -composite ^
  X2.png

... where mask.txt is ...

Code: Select all

# ImageMagick pixel enumeration: 2000,1000,255,srgb
1224,257: (0,0,0)
1224,259: (0,0,0)
1050,256: (0,0,0)
1057,256: (0,0,0)
1058,256: (0,0,0)

You can use X.png as the output as well as the input. But testing is harder when you destroy the input.

I show mask.txt with dimensions (2000,1000), but these must match the dimensions of X.png. Not a problem, as it would be built with a script.

Or you could use fmw's method, and create a text file or string (Windows "environment variable") of draw commands, and make the mask with that.

gadapchetvoi wrote:And I want to use Windows' commandline to convert all the above points(pixels) of "X.png" to grayscale but keep those point's alpha transparent.

If we use my technique above, we can add a facility to save and restore the alpha channel, but it is messy:

Code: Select all

convert ^
  X.png ^
  -set colorspace RGB ^
  ( +clone -channel Alpha -separate -write mpr:saveAlpha +delete ) ^
  ( +clone -modulate 100,0,100 mask.txt -compose CopyOpacity -composite -channel Alpha -negate ) ^
  -compose Over -composite ^
  -channel RGBA ^
  -separate ^
  mpr:saveAlpha ^
  -delete 3 ^
  -combine ^
  -set colorspace sRGB ^
  X2.png

snibgo wrote:

Code: Select all

convert ^
  X.png ^
  -set colorspace RGB ^
  ( +clone -channel Alpha -separate -write mpr:saveAlpha +delete ) ^
  ( +clone -modulate 100,0,100 mask.txt -compose CopyOpacity -composite -channel Alpha -negate ) ^
  -compose Over -composite ^
  -channel RGBA ^
  -separate ^
  mpr:saveAlpha ^
  -delete 3 ^
  -combine ^
  -set colorspace sRGB ^
  X2.png

Thanks a lot snibgo ! Your code worked like a charm!
But to say the truth, I've never ever imagined it must be so complicated !
Although it's pretty hard to understand, I owe you a beers for your awesome experience!

NOTE; When reading a Enumerated Pixel text file (.txt), anything not 'enumerated' will be set to the background color, whcih is white by default.

I suggest you set the background color appropriately.

Also. An easy way is to use that mask file as a Write Mask....
See Write masks..
http://www.imagemagick.org/Usage/masking/#write_mask

For example..

Code: Select all

convert X.png -background white -mask mask.txt -modulate 100,0,100 X2.png

that is a lot simplier!

To turn of the mask (for other processing use +mask.

WARNING: image masking in IMv7 will likely be different but greatly improved.

Legacy ImageMagick Discussions Archive

Turn a set of pixels into grayscale ?

Turn a set of pixels into grayscale ?

Re: Turn a set of pixels into grayscale ?

Re: Turn a set of pixels into grayscale ?

Re: Turn a set of pixels into grayscale ?

Re: Turn a set of pixels into grayscale ?

Re: Turn a set of pixels into grayscale ?

Re: Turn a set of pixels into grayscale ?

Re: Turn a set of pixels into grayscale ?

Re: Turn a set of pixels into grayscale ?