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This is, as opposed to some of my other tutorials, is a really quick one. Sometimes you want to improve the mood of your image, make it more alluring and interesting. You have light sources in there, but they simply don't look all that realistic. The colours of the whole thing looks cold and hard, despite your intentions.
The tutorial consists of three short parts, which you can use together or try out separately on your own images:
- Adding warm ambience -- change the overall mood of your image
- Adding point light source -- this is efficient for creating realistic "blinding" light effects.
- Adding a fantasy feel -- this uses layer effects to add even more to the mood and feel of the image.
This is the starting image (scaled down, so it's a bit lo-res here and there):
(finished image here[/img]).
The details and shadows have already been applied here, both local self-shadowing and global shadows. The image is practically finished. But it's also very cold in colour -- you can't really see that the fire is warming the room very much. She looks dead cold. Also, note that there are two candles close to us. They are currently unlit. We want to have candle light in them (in this particular image, the shadows have actually already been prepared to account for these candles beeing lit, but that's a different issue not covered here).
The idea is that you can use this tutorial with one of your own images; no need to try to replicate this one unless you really, really want to.
;Adding warm ambience
What we want to begin with is to remove that "coldness" of the image. The firelight is yellowish, it should influence this image.
Create a new layer above your image. This layer will act like a "glass plate" through which we will look at the painting. Use the fill tool to fill the glass plate layer with a yellow-ochra colour. Now set it to mode "Grain Merge" and start adjusting the opacity downwards. Some experimenting is required to make it fit your particular image.
This is the result of setting the opacity of our "glass plate" layer to 68%. Suddenly it's a lot warmer in there isn't it! Note that you can achieve many interesting results by creating a "coloured glass plate" such as this and experimenting with various modes. It all comes down to your original image; the effects can be quite striking.
Point light sources
Now we'll continue with the light sources. What we want is to have the light becoming slightly "blinding" to us as a viewer. This effect is created by allowing the light to actually subly cover the entire image. Read on ...
Create a new layer "Light fades" above your image and work on this.
Choose the Gradient fill tool, set it to 70% opacity. Pick the "radial" fill type.
Pick the FG->transparent gradient. This is shipped with GIMP by default. Pick the Foreground colour to be a whitish-yellow colour. This will make a nice smooth light source.
Choose your newly created gradient in the gradient fill tool and click and drag from the center of the light (the candle in this case) all the way out the the edge of the farthest edge of the image. If you want to enhance the effect, repeat a second time, maybe making the radius a little shorter to make the colour more concentrated.
Repeat for other light sources in the image, work on the same layer. They will blend nicely. Make sure you don't cover the background too much, lower the opacity of this layer to make the effect subtle.
This is the result:
I have applied the gradient twice for each candle: first all the way out to the edge of the picture, and secondly with a smaller radius to create the more intense "halos" of light close to the flames. Here, I've added the actual flames of the candles too. I did that on the same layer, but after this, remember not to touch this layer again -- because if you happen to erase something in here you will never be able to recreate those subtle gradients by hand. Leave this layer be as it is and work on other ones.
Note that light effects such as this are technically called "diffused light" and are dependent on the amount of dust and small particles in the air. In a room such as this -- with an open fire and old books all around -- it fits well to have light being a bit diffused. Outdoors you should often not see this effect because outside air is stirred by wind. Many a christmas drawing shows candles with a large halo around them even on a clear winter's day -- this is not correct physics. Same goes for a science-fiction image, at least if you depict some clinical metallic environment -- if the air is clean, light should not be diffused. The extreme of this is space -- if you ever draw light in space you will never have diffusion effects at all, since there is no atmosphere.
Adding a fantasy feel to the image
This is also called a "soft glow" or "bloom" effect and is already used in thousands of sigs I imagine. It's here for completeness.
Hide the layers with the light sources for this, because they will be over-exposed by this procedure if you include them.
We now want to operate on all of these visible layers in one go.
In the past versions of this tutorial this involved a lengthy merge maneuver in several steps in order to produce a merged layer without destroying the ingoing layers. These days (as pointed out by user Pixelated) one needs only one):
After having hidden the light fade layers, use the menu choice Layer->New from visible. There! You now have a new layer named "Visible" above all your old layers. It's often a good idea to keep your old layer structure saved away like this in case you want to change something later.
Apply a hefty blur on this new layer, like a gaussian blur (Filters->Blur->Gaussian Blur...) at horizontal and vertical value of 50 or so.
Next it's all about choosing the mode (and opacity) of this layer to fit what you want. Using a 70% opacity, The "Screen" mode will brighten the image to give a classical "Fantasy glow" (or "bloom") like this:
This is probably a bit too much bloom to be useful, but the effect is clear. I wanted a less saturated effect though, so I set the layer to "Burn" instead, producing this (final) outcome:
Final points
I suppose many of these tricks are used already in your sig-making and are maybe not new to many of you. But I don't think it's so often seen how it can be used in a larger work too. The difference is that whereas a sig tends to show off the effects being used, an artistic piece should ideally (at least in my opinion) not scream out "digital effect!"! if it can be avoided. The digital effects are there only to spruce up and enhance the image, they should not be the image.
Hope this gave some ideas for use with your own pictures.
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Griatch
