Help me please ^^ .I need to check pen's color on image

Excute me, I need your help. Anyone can give me some algorithm or some idea for check blue color of pen on this image? I need to check blue color cross that name on this image.if that name crossed by blue's pen color I provide that name is absences ^^

[Jan]

Please show us an example image.

Answer 1

[Image Analyst]

It should be an easy adaptation of one of the color segmentation demos in my File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

I don't know what "I provide that name is absences" means but I guess you just need to see if some name, presumably written black, has blue ink on top of it. A simple way would be to just convert to hsv color space and look for any pixels with a hue in the blue range. Post your image. Also let us know why you're doing this, for example it's a class assignment, needed for your Ph.D. work or your company, or whatever.

[Saroj Boonprom]

Thank you for your answer. I'm study in University of Thailand. :D . I don't know how to explain. I make the project about this. Now I do about grid by function writing for check this pixel. I think this picture help me to explain about this :) . Sorry my English not strong ^^ I try to train Eng word. :) oh I'm forgot. about "I provide that name is absences".I make project about "Name Check the course system with Image Processing"

Thank you for your answer again ^^

[Saroj Boonprom]

I make HSV Picture :) and create black line =-=

[Image Analyst]

My code will find them. You just need to combine the channels. You need hue in a certain range, and probably high saturation values and low "value image" values. That will get just the pen marks and not include white pixels that are blue hue, like pixels with RGB values of [230, 230, 232] which is evidently what you're picking up in the white areas. My demo goes into how you can combine channels to carve out exactly the part of the 3D color gamut that you need.