Re: lingo-l GetPixel() to compare colors
On Wednesday, June 4, 2003, at 01:53 PM, Rodrigo Peres wrote: I'm using getPixel to compare 2 images and return the differences between them. After I run a list of points and check if some points are diferent from the bgcolor (white). The problem: The image is scanned so there's a lot of dust confusing the getPixel(). There's a way to compare if colors are greater than or darker than??? Example My background color is white (255,255,255) and if the pixel I test is close to gray or black (0,0,0) it is diferent. Hi Rodrigo, If you need to compare a large number of pixels, you will find it much faster to use copyPixels() rather than getPixels(). CopyPixels() is like a SCUBA diver: it can dive into Director's C++ imaging routines and do a lot of work on a lot of pixels at once. GetPixel() is like a skin diver: it wastes a lot of time coming back up to Lingo for air between each operation. You'll find below a handler that might be useful to you. It compares two images and returns an integer in the range -1 - 255. A value of -1 indicates that the images are different sizes; a value of 0 indicates that they are identical. Any other value indicates the maximum difference between any two identically placed pixels. For example, if the two images are identical except for one pixel which is white in one image and black in the other, the output will be 255. The same output value of 255 could occur for white+black, red+yellow, green+blue, and a number of other mis-matches. The value reflects the biggest difference in either the red, green or blue values for the mis-matching pixels. On the other hand, if one image shows white clouds and the other a snowy landscape, the output may be only (say) 89. This would indicate that no identically placed pixels have that great a difference in color, even though the images themselves appear completely different to us humans. You could run a number of tests on different scans of the same image to determine what level of tolerance you need to apply. You could then use the handler to compare images, and reject pairs whose tolerance exceeds your chosen value. If you need to compare the contents of the images, you could break the images up into smaller sections and compare these. Cheers, James -- on getTolerance(anImage, anotherImage) --- -- INPUT: anImage and anotherImage must both be image objects of -- the same size. -- OUTPUT: An integer indicating the maximum difference in red, -- green or blue for any individual pixel in the two images. -- If the images are identical, 0 is returned. If the -- images are different sizes, -1 is returned. -- Ensure that the two images are the same size tRect = anImage.rect if anotherImage.rect tRect then return -1 end if -- Create a 32-bit image in which to perform comparisons tCompare = image(tRect.width, tRect.height, 32) tCompare.copyPixels(anImage, tRect, tRect) -- Create an image which shows the differences between the images tCompare.copyPixels(anOtherImage, tRect, tRect, [#ink: #reverse]) if not tCompare.trimWhiteSpace().width then -- Images are identical return 0 end if tPixel = image(1, 1, 32) tWidth = 1 tIncrement = 128 -- Test in 8 steps of increasing precision repeat while tIncrement if tWidth then -- Not enough attenuation was used for the last test tTolerance = tTolerance + tIncrement else -- Check whether too much attenuation was used for the last test tTolerance = tTolerance - tIncrement end if -- Attenuate the difference image and check if all pixels go white tPixel.setPixel(0, 0, rgb(tTolerance, tTolerance, tTolerance)) tTest = tCompare.duplicate() tTest.copyPixels(tPixel, tRect, rect(0,0,1,1), [#ink: #addPin]) tTest = tTest.trimWhiteSpace() tWidth = tTest.width -- will be zero if all pixels are now white -- Increase the precision for the next test tIncrement = tIncrement / 2 end repeat return tTolerance + (tWidth 0) -- + 1 if last test failed end getTolerance [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
BTW, if you don't have James' book I highly recommend it. Plenty of nice imaging lingo stuff. Kerry's and Gretchen's reviews at Amazon say it all. http://www.amazon.com/exec/obidos/tg/detail/-/0072132655/104-9270019- 9338345?vi=glance Joe On Thursday, Jun 5, 2003, at 12:01 US/Eastern, James Newton wrote: Hi Rodrigo, If you need to compare a large number of pixels, you will find it much faster to use copyPixels() rather than getPixels(). CopyPixels() is like a SCUBA diver: it can dive into Director's C++ imaging routines and do a lot of work on a lot of pixels at once. GetPixel() is like a skin diver: it wastes a lot of time coming back up to Lingo for air between each operation. [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
lingo-l GetPixel() to compare colors
Hi list, I'm using getPixel to compare 2 images and return the differences between them. After I run a list of points and check if some points are diferent from the bgcolor (white). The problem: The image is scanned so there's a lot of dust confusing the getPixel(). There's a way to compare if colors are greater than or darker than??? Example My background color is white (255,255,255) and if the pixel I test is close to gray or black (0,0,0) it is diferent. Thank's Rodrigo [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
On Wednesday, Jun 4, 2003, at 08:53 America/Chicago, Rodrigo Peres wrote: There's a way to compare if colors are greater than or darker than??? Try using color objects and palette index conversions: oColor = color(#rgb, 255,255,255) oColor2 = color(#rgb, 0,0,0) put oColor.paletteIndex oColor2.paletteIndex -- 0 put oColor.paletteIndex oColor2.paletteIndex -- 1 Warren Ockrassa | President, nightwares LLC [EMAIL PROTECTED] nightwares LLC | Consulting Programming http://www.nightwares.com/ Developer | Structor, a presentation development/programming tool Info and demo | http://www.nightwares.com/structor/ Author | Director 8.5 Shockwave Studio: A Beginner's Guide Chapter samples | http://www.nightwares.com/director_beginners_guide/ [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
Howdy-Tzi wrote: On Wednesday, Jun 4, 2003, at 08:53 America/Chicago, Rodrigo Peres wrote: There's a way to compare if colors are greater than or darker than??? Try using color objects and palette index conversions: oColor = color(#rgb, 255,255,255) oColor2 = color(#rgb, 0,0,0) put oColor.paletteIndex oColor2.paletteIndex -- 0 put oColor.paletteIndex oColor2.paletteIndex -- 1 Works in the extreme case, but it gets shaky in the middle values unless you're using the greyscale palette: cyan = color(#rgb, 0, 255, 255) dkcyan = color(#rgb, 0, 204, 255) dkbrn = color(#rgb, 51, 0, 0) -- System - Win palette put cyan.paletteIndex -- 1 put dkbrn.paletteIndex -- 179 put dkcyan.paletteIndex -- 184 -- System - Mac palette put cyan.paletteIndex -- 180 put dkbrn.paletteIndex -- 179 put dkcyan.paletteIndex -- 186 -- Greyscale palette put cyan.paletteIndex -- 85 put dkbrn.paletteIndex -- 238 put dkcyan.paletteIndex -- 102 -- Carl West [EMAIL PROTECTED] http://eisen.home.attbi.com I have no superfluous leisure; my stay must be stolen out of other affairs; but I will attend you awhile. - Isabella, Measure for Measure, Act 3 Scene 1 - [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
There's a way to compare if colors are greater than or darker than??? Try using color objects and palette index conversions: oColor = color(#rgb, 255,255,255) oColor2 = color(#rgb, 0,0,0) put oColor.paletteIndex oColor2.paletteIndex -- 0 put oColor.paletteIndex oColor2.paletteIndex -- 1 Curious. How does the color object know what palette to use? The movie's default palette? A coworker asked me the same question, just today. -- Cole [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
Here's a possibly good way to do it (I say possibly, because I didn't test it, but it feels like it ought to work). If you're using 8.5 or later, you could do this: c1 = rgb(100,100,100) c2 = rgb(123,100,100) v1 = vector(c1.red,c1.green,c1.blue) v2 = vector(c2.red,c2.green,c2.blue) put v1.distanceto(v2) -- 23. You would count colors as being the same if their distance from the comparison color is less than a certain amount. [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
On Wednesday, Jun 4, 2003, at 12:10 America/Chicago, Cole Tierney wrote: There's a way to compare if colors are greater than or darker than??? Try using color objects and palette index conversions: oColor = color(#rgb, 255,255,255) oColor2 = color(#rgb, 0,0,0) put oColor.paletteIndex oColor2.paletteIndex -- 0 put oColor.paletteIndex oColor2.paletteIndex -- 1 Curious. How does the color object know what palette to use? Oops. Looks like MX has changed things a bit. Used to be that the paletteIndex value could return a number into the millions if you were at 24-bit + color. HOWever, you can carry out the same comparisons using hexString(): oColor = color(#rgb, 0,0,0) put oColor.hexstring() -- #00 oColor2 = color(#rgb, 255,255,255) put oColor2.hexString() -- #FF put oColor.hexString() oColor2.hexString() -- 0 put oColor.hexString() oColor2.hexString() -- 1 That should take care of any funky mid-shade colors. Warren Ockrassa | President, nightwares LLC [EMAIL PROTECTED] nightwares LLC | Consulting Programming http://www.nightwares.com/ Developer | Structor, a presentation development/programming tool Info and demo | http://www.nightwares.com/structor/ Author | Director 8.5 Shockwave Studio: A Beginner's Guide Chapter samples | http://www.nightwares.com/director_beginners_guide/ [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
oColor = color(#rgb, 0,0,0) put oColor.hexstring() -- #00 oColor2 = color(#rgb, 255,255,255) put oColor2.hexString() -- #FF put oColor.hexString() oColor2.hexString() -- 0 put oColor.hexString() oColor2.hexString() -- 1 Don't know if you would want to work this way. A color of rgb(0,255,255), full brightness cyan, may seem to be closer to black than rgb(1,0,0), almost completely black, would be. [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
Colin Holgate wrote: Here's a possibly good way to do it (I say possibly, because I didn't test it, but it feels like it ought to work). If you're using 8.5 or later, you could do this: c1 = rgb(100,100,100) c2 = rgb(123,100,100) v1 = vector(c1.red,c1.green,c1.blue) v2 = vector(c2.red,c2.green,c2.blue) put v1.distanceto(v2) -- 23. You would count colors as being the same if their distance from the comparison color is less than a certain amount. Rodrigo asked: There's a way to compare if colors are greater than or darker than??? To compare lightness/darkness you'd need to get their distances from vector(0,0,0) and compare those Just totaling the r,g, and b values should give a reasonable measure of the lightness of a pixel. -- Carl West [EMAIL PROTECTED] http://eisen.home.attbi.com I have no superfluous leisure; my stay must be stolen out of other affairs; but I will attend you awhile. - Isabella, Measure for Measure, Act 3 Scene 1 - [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
Here's a possibly good way to do it (I say possibly, because I didn't test it, but it feels like it ought to work). If you're using 8.5 or later, you could do this: c1 = rgb(100,100,100) c2 = rgb(123,100,100) v1 = vector(c1.red,c1.green,c1.blue) v2 = vector(c2.red,c2.green,c2.blue) put v1.distanceto(v2) -- 23. You would count colors as being the same if their distance from the comparison color is less than a certain amount. Nice. This seems to make the most conceptual sense, since the rgb color model is described in terms of 3d space. Performance might be a problem, though. -- Cole [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
Nice. This seems to make the most conceptual sense, since the rgb color model is described in terms of 3d space. Performance might be a problem, though. You could do your own Pythagoras out of the rgb values, and cut out the vector conversion. Not sure if that would be faster than the build in distanceto function. [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
Re: lingo-l GetPixel() to compare colors
On Wednesday, Jun 4, 2003, at 13:36 America/Chicago, Colin Holgate wrote: Don't know if you would want to work this way. A color of rgb(0,255,255), full brightness cyan, may seem to be closer to black than rgb(1,0,0), almost completely black, would be. Sigh. It's jut not my day it seems. You're right of course. This is what happens when I try to edit and think about code at the same time... -- WthmO [To remove yourself from this list, or to change to digest mode, go to http://www.penworks.com/lingo-l.cgi To post messages to the list, email [EMAIL PROTECTED] (Problems, email [EMAIL PROTECTED]). Lingo-L is for learning and helping with programming Lingo. Thanks!]
