Here's some specifics of the blend modes. https://en.wikipedia.org/wiki/Blend_modes http://www.linuxtopia.org/online_books/graphics_tools/gimp_advanced_guide/gimp_guide_node55_002.html For your example pictures, screen will over brighten the darker areas of your picture, so dodge produces a better result. In a different picture, screen could be the better choice. Brian On 03/23/2016 12:56 PM, Michael wrote: > please, what is the difference between the two modes? > > On Wed, Mar 23, 2016 at 2:35 PM, Brian Cluff > wrote: > > Oops, use the Dodge layer mode instead of screen. You'll get better > results. > > Brian > > > On 03/23/2016 11:22 AM, Brian Cluff wrote: > > > On 03/23/2016 04:49 AM, Michael wrote: > > Thanks Brian. I am putty in your hands! > > I get the bounces from the PLUG mailing list, so I got your > images even > though they were too big for the queue... nobody else did > though, so my > answer will be the only one based off your image. > > Anyway, looking at your pictures, it appears that the darkened edges > aren't due to fading over time rather they are caused by what > appear to > be a flash going off that lit the center of the image more than the > edges. This can also be caused of lower quality lenses giving you > darkened edges in what is called a vignette. > > If you want to try and reduce/eliminate it, in gimp you would add a > layer above your picture, but before you do that, if you have the > option, go to Image -> Precision and set it to 16 ot 32 bit, so > that you > have more color data to work with. Unfortunately you'll only > have that > option if you are running the development version of GIMP, but > it will > still work OK if you can't do that setting. Next use the > gradient tool, > changing the gradient type to radial, and make a gradient that > goes from > black in the center fading to white at the corners. (draw the > gradient > from the center to one of the corners). > > Then set your new gradient layer's mode to "screen". > > At this point the effect will probably be too strong, so you > will need > to play with the opacity till it looks better and you can also > play with > the color curves moving the line on the lower left back and > forth across > the bottom to adjust the shape of the gradient till it better > matches > the vignette in your image. You can change the gradients layer mode > back to normal to get an idea of what the color curve adjustment is > doing to the gradient. > > Brian Cluff > > On 03/22/2016 06:42 PM, Brian Cluff wrote: > > Can you send an example so that I can see what you mean by > "darkened > around the edges"? > > I'll see if I can easily correct it and then send > instructions on what I > did. > > Brian Cluff > > On 03/22/2016 04:18 PM, Michael wrote: > > how does one use a transparent layer? is it only for > drawing things on? > I have some old pictures that have darkened around the > edges. How I > think I can fix it is to duplicate the layer then > lighten the exposure > value on the lower image, then paint black and uncover > the lighter image > over the section that has darkened. How do I do this > with gradients and > Darktable? > > -- > :-)~MIKE~(-: > > > --------------------------------------------------- > PLUG-discuss mailing list - > PLUG-discuss@lists.phxlinux.org > > To subscribe, unsubscribe, or to change your mail settings: > http://lists.phxlinux.org/mailman/listinfo/plug-discuss > > --------------------------------------------------- > PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org > > To subscribe, unsubscribe, or to change your mail settings: > http://lists.phxlinux.org/mailman/listinfo/plug-discuss > > --------------------------------------------------- > PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org > > To subscribe, unsubscribe, or to change your mail settings: > http://lists.phxlinux.org/mailman/listinfo/plug-discuss > > --------------------------------------------------- > PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org > > To subscribe, unsubscribe, or to change your mail settings: > http://lists.phxlinux.org/mailman/listinfo/plug-discuss > > > > > -- > :-)~MIKE~(-: > > > --------------------------------------------------- > PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org > To subscribe, unsubscribe, or to change your mail settings: > http://lists.phxlinux.org/mailman/listinfo/plug-discuss > --------------------------------------------------- PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org To subscribe, unsubscribe, or to change your mail settings: http://lists.phxlinux.org/mailman/listinfo/plug-discuss