You may try Colors -> Component -> Decompose, then select LAB space, BW image is the L, thats a lot better than anything else I have tried
Regards -----Original Message----- From: Lancer <for...@gimpusers.com> To: gimp-user-list@gnome.org Cc: notificati...@gimpusers.com Date: Tue, 06 Jun 2017 06:02:29 +0200 Subject: [Gimp-user] When black and white is not black and white I am a school teacher. One of the checks I ask students to do in order to test the contrast of their graphics work, is to convert the images to grayscale and see whether images are still clear. There are two methods students are using to convert their images to grayscale for this test... Method 1: flatten image, then Colors > Hue-Saturation => slide the saturation slider down to zero. Method 2: image => mode => grayscale Either of these methods results in a grayscale image, but the grays are not exactly the same. For example, if I have absolute red (#FF0000) next to blue, the grayscaled-blue may match the grayscaled-red depending on the tone *and* the method used. Method 1: Absolute red (#FF0000) will grayscale-match absolute blue (#0000FF) Method 2: Absolute red (#FF0000) will grayscale-match a slightly lighter shade of blue (#2626FF) Why are the two methods of grayscale having a different result? I would have thought that conversion to grayscale would be the same process as dragging down the saturation of an image. ...and given that they are different, which is the better method to use in terms of testing for contrast in media assignments? -- Lancer (via www.gimpusers.com/forums) _______________________________________________ gimp-user-list mailing list List address: gimp-user-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list List archives: https://mail.gnome.org/archives/gimp-user-list _______________________________________________ gimp-user-list mailing list List address: gimp-user-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list List archives: https://mail.gnome.org/archives/gimp-user-list
