Re: Find nearest color in an RGB list
Yeay! One always worries about code written IN the email... :) ~ Nonsanity On Tue, Jan 10, 2012 at 3:31 PM, Michael Doub m...@doub.com wrote: This works like a charm! Thanks, Mike On 2012-01-10, at 3:03 PM, Nonsanity wrote: Both look like good suggestions for getting the closest color a human would think is a match, but both involve converting Livecode's native RGB to another format. I may be wrong, but I don't think those conversions are available built-in. I'm sure functions have been written to do this many times, but it's not trivial to do from scratch. If you can get one, then the following code will still work - It'll just work better. (Replace the r, g, b variable names with the appropriate letters for clarity.) Depending on your use case, you may not need to be that human-accurate, in which case you can do the same calculation in RGB space. The square root calculation in your two solutions is a way to get the distance between any two points in three dimensional space. All three color formats have three values, so they can all be pictured as a cube of space with colors as points within that space. Your starting color is in there too, and you just have to check the distance from it to all the other color points, and return the shortest. I'm typing this in a mail program, so it is untested... function Distance3D( x1, y1, z1, x2, y2, z2 ) return sqrt( (x1-x2)*(x1-x2) + (y1-y2)*(y1-y2) + (z1-z2)*(z1-z2) ) end Distance3D function GetClosestColor( r, g, b ) put 9 into ClosestDist put r , g , b into ClosestColor repeat for each line c of gColorList get Distance3D( r, g, b, item 1 of c, item 2 of c, item 3 of c ) if it ClosestDist then put it into ClosestDist put c into ClosestColor end if end repeat return ClosestColor end GetClosestColor You'd have your colors in gColorList like this: 32,32,128 255,255,255 0,0,0 128,128,256 (etc) ~ Chris Innanen ~ Nonsanity On Tue, Jan 10, 2012 at 1:13 PM, Michael Doub m...@doub.com wrote: I have a list of RGB colors that represent different color samples. I need to create a function that will return the closest perceived RGB entry in the list when supplied a single RGB value. Is anyone aware of a library or some sample code that would help with this task? From searching I found the follow two suggestions for solving this problem. Neither are not intuitively obvious to the casual observer...namely me. ;-) 1) Convert RGB to CIE Lab color space, then compute the distance in that space ( deltaE = sqrt(deltaL^2 + deltaA^2 + deltaB^2). Colors with the lowest deltaE are the most perceptually similar to each other. 2) Convert to RGB to HSL and consider an HSL color value a vector and define a weighted modulus function for the vector like this: modulus = sqrt(a*H1*H1 + b*S1*S1 + c*L1*L1); where a,b,c are weights you should decide based on your visual definition of what creates a bigger difference in perceived color - a 1% change in Hue or a 1% change in Saturation. I would suggest you use a = b = 0.5 and c = 1 Finally, find out the range your modulus would take and define similar colors to be those which have their moduli very close to each other (say 5%) Regards, Mike ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
Find nearest color in an RGB list
I have a list of RGB colors that represent different color samples. I need to create a function that will return the closest perceived RGB entry in the list when supplied a single RGB value. Is anyone aware of a library or some sample code that would help with this task? From searching I found the follow two suggestions for solving this problem. Neither are not intuitively obvious to the casual observer...namely me. ;-) 1) Convert RGB to CIE Lab color space, then compute the distance in that space ( deltaE = sqrt(deltaL^2 + deltaA^2 + deltaB^2). Colors with the lowest deltaE are the most perceptually similar to each other. 2) Convert to RGB to HSL and consider an HSL color value a vector and define a weighted modulus function for the vector like this: modulus = sqrt(a*H1*H1 + b*S1*S1 + c*L1*L1); where a,b,c are weights you should decide based on your visual definition of what creates a bigger difference in perceived color - a 1% change in Hue or a 1% change in Saturation. I would suggest you use a = b = 0.5 and c = 1 Finally, find out the range your modulus would take and define similar colors to be those which have their moduli very close to each other (say 5%) Regards, Mike ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
Re: Find nearest color in an RGB list
Both look like good suggestions for getting the closest color a human would think is a match, but both involve converting Livecode's native RGB to another format. I may be wrong, but I don't think those conversions are available built-in. I'm sure functions have been written to do this many times, but it's not trivial to do from scratch. If you can get one, then the following code will still work - It'll just work better. (Replace the r, g, b variable names with the appropriate letters for clarity.) Depending on your use case, you may not need to be that human-accurate, in which case you can do the same calculation in RGB space. The square root calculation in your two solutions is a way to get the distance between any two points in three dimensional space. All three color formats have three values, so they can all be pictured as a cube of space with colors as points within that space. Your starting color is in there too, and you just have to check the distance from it to all the other color points, and return the shortest. I'm typing this in a mail program, so it is untested... function Distance3D( x1, y1, z1, x2, y2, z2 ) return sqrt( (x1-x2)*(x1-x2) + (y1-y2)*(y1-y2) + (z1-z2)*(z1-z2) ) end Distance3D function GetClosestColor( r, g, b ) put 9 into ClosestDist put r , g , b into ClosestColor repeat for each line c of gColorList get Distance3D( r, g, b, item 1 of c, item 2 of c, item 3 of c ) if it ClosestDist then put it into ClosestDist put c into ClosestColor end if end repeat return ClosestColor end GetClosestColor You'd have your colors in gColorList like this: 32,32,128 255,255,255 0,0,0 128,128,256 (etc) ~ Chris Innanen ~ Nonsanity On Tue, Jan 10, 2012 at 1:13 PM, Michael Doub m...@doub.com wrote: I have a list of RGB colors that represent different color samples. I need to create a function that will return the closest perceived RGB entry in the list when supplied a single RGB value. Is anyone aware of a library or some sample code that would help with this task? From searching I found the follow two suggestions for solving this problem. Neither are not intuitively obvious to the casual observer...namely me. ;-) 1) Convert RGB to CIE Lab color space, then compute the distance in that space ( deltaE = sqrt(deltaL^2 + deltaA^2 + deltaB^2). Colors with the lowest deltaE are the most perceptually similar to each other. 2) Convert to RGB to HSL and consider an HSL color value a vector and define a weighted modulus function for the vector like this: modulus = sqrt(a*H1*H1 + b*S1*S1 + c*L1*L1); where a,b,c are weights you should decide based on your visual definition of what creates a bigger difference in perceived color - a 1% change in Hue or a 1% change in Saturation. I would suggest you use a = b = 0.5 and c = 1 Finally, find out the range your modulus would take and define similar colors to be those which have their moduli very close to each other (say 5%) Regards, Mike ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
Re: Find nearest color in an RGB list
This works like a charm! Thanks, Mike On 2012-01-10, at 3:03 PM, Nonsanity wrote: Both look like good suggestions for getting the closest color a human would think is a match, but both involve converting Livecode's native RGB to another format. I may be wrong, but I don't think those conversions are available built-in. I'm sure functions have been written to do this many times, but it's not trivial to do from scratch. If you can get one, then the following code will still work - It'll just work better. (Replace the r, g, b variable names with the appropriate letters for clarity.) Depending on your use case, you may not need to be that human-accurate, in which case you can do the same calculation in RGB space. The square root calculation in your two solutions is a way to get the distance between any two points in three dimensional space. All three color formats have three values, so they can all be pictured as a cube of space with colors as points within that space. Your starting color is in there too, and you just have to check the distance from it to all the other color points, and return the shortest. I'm typing this in a mail program, so it is untested... function Distance3D( x1, y1, z1, x2, y2, z2 ) return sqrt( (x1-x2)*(x1-x2) + (y1-y2)*(y1-y2) + (z1-z2)*(z1-z2) ) end Distance3D function GetClosestColor( r, g, b ) put 9 into ClosestDist put r , g , b into ClosestColor repeat for each line c of gColorList get Distance3D( r, g, b, item 1 of c, item 2 of c, item 3 of c ) if it ClosestDist then put it into ClosestDist put c into ClosestColor end if end repeat return ClosestColor end GetClosestColor You'd have your colors in gColorList like this: 32,32,128 255,255,255 0,0,0 128,128,256 (etc) ~ Chris Innanen ~ Nonsanity On Tue, Jan 10, 2012 at 1:13 PM, Michael Doub m...@doub.com wrote: I have a list of RGB colors that represent different color samples. I need to create a function that will return the closest perceived RGB entry in the list when supplied a single RGB value. Is anyone aware of a library or some sample code that would help with this task? From searching I found the follow two suggestions for solving this problem. Neither are not intuitively obvious to the casual observer...namely me. ;-) 1) Convert RGB to CIE Lab color space, then compute the distance in that space ( deltaE = sqrt(deltaL^2 + deltaA^2 + deltaB^2). Colors with the lowest deltaE are the most perceptually similar to each other. 2) Convert to RGB to HSL and consider an HSL color value a vector and define a weighted modulus function for the vector like this: modulus = sqrt(a*H1*H1 + b*S1*S1 + c*L1*L1); where a,b,c are weights you should decide based on your visual definition of what creates a bigger difference in perceived color - a 1% change in Hue or a 1% change in Saturation. I would suggest you use a = b = 0.5 and c = 1 Finally, find out the range your modulus would take and define similar colors to be those which have their moduli very close to each other (say 5%) Regards, Mike ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
