Re: [Gimp-user] how to invert greyscale values only... leaving colors alone
On Mon, 2010-02-01 at 15:27 -0800, Rich Evans wrote: > Hello, Is this the right place to ask a question about special filters in > GIMP? If so, I'd love some advice on the following task: > > I have an RGB image that is basically a black background with many > colorful objects and white text. --- I'd like to invert the image so > that it is a white background with black text but a simple invert > inverts the colors in all the colored objects as well. Is there a > technique or tool to invert any part of the image that is only a shade > of grey? i.e. invert pixeils with a saturation of ~0 (if that is how > you say it). I could imagine a filter that does a simple RGB invert > for any pixel whose calculated RGB saturation value is below a set > threshold. Does this type of tool/script exist? Simple. First create a duplicate of your layer. Then invert the colors on the lower layer and set the layer mode of the upper (unchanged) layer to "Colors". Sven ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] how to invert greyscale values only... leaving colors alone
Rich Evans wrote: > I have an RGB image that is basically a black background with many colorful > objects and white text. --- I'd like to invert the image so that it is a > white background with black text but a simple invert inverts the colors in > all the colored objects as well. Is there a technique or tool to invert any > part of the image that is only a shade of grey? i.e. invert pixeils with a > saturation of ~0 (if that is how you say it). I could imagine a filter that > does a simple RGB invert for any pixel whose calculated RGB saturation value > is below a set threshold. Does this type of tool/script exist? Here's how I'd do this: First, I'd make a copy of the original image. Second, working with the copy, I'd add a new layer, filled with white, and move that layer to the bottom of the layer stack. Third, I'd make a copy of the original image, and move the copy to the top of the stack, if it doesn't happen to be there at the beginning. If necessary, I'd switch the color paletes so that black is the active color. Then I'd use the facility to select by color tool to select the white areas, making certain that there were not highlights of some of the "many colorful objects" which got included as well. I'd then paint or bucket fill as necessary to convert the formerly white areas to black. Fourth, returning to the original layer, I'd select all of the areas which are black, and remove them. Finally, merge the layers together, and you should have achieved the effect you wish. ns ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
[Gimp-user] how to invert greyscale values only... leaving colors alone
Hello, Is this the right place to ask a question about special filters in GIMP? If so, I'd love some advice on the following task: I have an RGB image that is basically a black background with many colorful objects and white text. --- I'd like to invert the image so that it is a white background with black text but a simple invert inverts the colors in all the colored objects as well. Is there a technique or tool to invert any part of the image that is only a shade of grey? i.e. invert pixeils with a saturation of ~0 (if that is how you say it). I could imagine a filter that does a simple RGB invert for any pixel whose calculated RGB saturation value is below a set threshold. Does this type of tool/script exist? thanks! -Rich (revansx) ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
