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  • X Http User Agent Mozilla 4 0 compatible MSIE 4 01 Windows NT In article Rafal wrote Tom Clune wrote In article Rafal wrote Hallo I wont to use my filters on colored digital images But all algorithms which I have are for grayed images How can I use this algoriths for colored images I don t know how other people do it but I always convert to YUV color space and only filter the Y grayscale data After filtering you can switch back to RGB if you like Trying to filter color images directly can give you some funny artifacts in the color Thanks In my book I found only YIQ color space Can you send me the matrix for converting from RGB YUV Or ist YUV equal to YIQ I m not familiar with YIQ But if the Y is just luminance it should do Here s my comment from the code I use to do the conversion R is the red color value G is the green color value and B is the blue color value All colors are 8 bit If your color depth varies change the 128 value accordingly BTW YCbCr YUV calculate the YCbCr

    Original URL path: http://www.efg2.com/Lab/Library/UseNet/1999/0430a.txt (2016-02-14)
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  • Lines 41 Message ID References NNTP Posting Host 194 221 231 1 Content Type text plain charset ISO 8859 1 Content Transfer Encoding 8bit X Trace posting google com 1039117166 12686 127 0 0 1 5 Dec 2002 19 39 26 GMT X Complaints To groups abuse google com NNTP Posting Date 5 Dec 2002 19 39 26 GMT Xref newsmst01 news prodigy com comp graphics algorithms 141877 vishak postmark net Vishak wrote in message news I am in the look out for the equation algorithm to convert CMYK to GrayScale Any sort of pointers sample code is highly appriciated Thanks in Advance Vishak Warning In one of the posts you will find this link http www easyrgb com math html Don t believe the wisdom there a CMYK to CMY depends on the UCR GCR mode Undercolor Removal Gray Component Replacement This is the strategy how much of the common value of C M Y is replaced by K b The so called dot gain is not taken into account This says use lower CMYK numbers because the dot becomes larger on the paper c CMY to RGB depends on gamut compression gamut clipping RGB primaries definition white point

    Original URL path: http://www.efg2.com/Lab/Library/UseNet/2002/1205.txt (2016-02-14)
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  • you need the values for one possible example of a Munsell N 8 or for the theoretical aim spectral curve Munsell Value 8 is the same as CIELAB L 80 L 116 Y 100 1 3 16 setting L 80 we can back solve for Y Y 100 L 16 116 3 Since we are dealing with a gray a Y of 80 can be obtained by a reflectance curve

    Original URL path: http://www.efg2.com/Lab/Library/UseNet/1999/0930a.txt (2016-02-14)
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  • that only need intensity informations no color motion I think you can find cat man and woman data sets that were processed the same way This may be true but the long run the YCrCb model seems much better then the RGB model I looked around and there was no good argument to use RGB but a few to use the YCrCb oder the HSV model I spent quite some time examining color spaces for image processing YCbCr is not bad as are all the Y B Y R Y derived color spaces However I have to agree strongly with Ohta et al 1 in their quite famous paper They did PCA s on several images and concluded finally that the color space I1I2I3 is the best generic color space for image processing The best color space for individual images is of course the space derived from the PCA The I1I2I3 space is defined as follows I1 1 3 1 3 1 3 R I2 1 2 0 1 2 G I3 1 4 1 2 1 4 B In fact I tried Ohtas tests on a great variety of images and got similar results as Ohta However I tested

    Original URL path: http://www.efg2.com/Lab/Library/UseNet/1999/0422b.txt (2016-02-14)
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  • UVW Color Space you are referring to is the CIE 1964 U V W system Gunter Wyszecki detailed this system in a paper which appeared in JOSA Journal of the Optical Society of America in 1963 Volume 53 page 1318 This system was based on the CIE 1960 UCS Diagram In 1976 this space was superceded by CIELUV Based on the CIE 1976 UCS Chromaticity Diagram This newer diagram is

    Original URL path: http://www.efg2.com/Lab/Library/UseNet/1999/1209b.txt (2016-02-14)
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  • 1294 213 97 41 5 13 Aug 2002 17 11 17 GMT X Complaints To usenet nsnmrro2 gest nuria telefonica data net NNTP Posting Date Tue 13 Aug 2002 17 11 17 0000 UTC X Priority 3 X MSMail Priority Normal X Newsreader Microsoft Outlook Express 6 00 2600 0000 X MimeOLE Produced By Microsoft MimeOLE V6 00 2600 0000 Xref newsmst01 news prodigy com sci engr color 6823 Hi

    Original URL path: http://www.efg2.com/Lab/Library/UseNet/2002/0813.txt (2016-02-14)
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    Original URL path: http://www.efg2.com/Lab/Library/UseNet/2001/0714.txt (2016-02-14)
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  • Oct 1999 13 07 49 GMT Newsgroups sci engr color One intention of the L a b formulation is that when you calculate delta E sqrt delta L 2 delta a 2 delta b 2 a delta E 1 should be just barely percievable to some viewers If you want most people to be able to distinguish between two colors most of the time a delta E 3 is needed Delta E 3 is called a MPCD minimum perceptible color difference or a JND just noticable difference by some authors Keep in mind that the L a b space is not a perfectly uniform space so the delta E value that is percievable depends on location in x y space and the direction between the two colors Using a delta E 1 threshold M R Pointer The Number of Discernible Colours Color Research and Application 23 1 February 1998 calculated that there are 2 28 million discernable color luminance combinations Other studies see references in Pointer show that printing inks give 1 6 million colors and EBU phosphors give 1 35 million colors These are far less than the 16 million colors claimed by 8 bit color video cards never

    Original URL path: http://www.efg2.com/Lab/Library/UseNet/1999/1001b.txt (2016-02-14)
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