> Just keep in mind that the book on linuxtopia, grokking the gimp, is 16
> years old. I'm sure there are plenty of good examples, but the gimp has
> changed significantly since then, so you might have to do a little
> searching for features that have moved.
>
> Brian Cluff
>
> On March 23, 2016 7:12:40 PM MST, Michael <bmike1@gmail.com> wrote:
>
>> I think I'll spend a day (week?) reading the Linuxtopia book.
>>
>> On Wed, Mar 23, 2016 at 4:13 PM, Brian Cluff <brian@snaptek.com> wrote:
>>
>>> 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 <brian@snaptek.com
>>>> <mailto:brian@snaptek.com>> 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~(-:
>>>>
>>>>
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>>>> --
>>>> :-)~MIKE~(-:
>>>>
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>>
>>
>> --
>> :-)~MIKE~(-:
>>
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