In this tutorial I'll show you how to add simulated film grain to your
digital images using the GIMP. To get an idea of what I am talking
about, examine the before and after images above, comparing the wall,
jacket, hat and face closely.
|
Load your image into the GIMP. If you are looking to make a
B&W image from a color image, you will first want to
convert it to B&W. Note that
you will need to convert the image back to RGB mode for this
technique, however...
I thought this portrait of a good-natured street musician might
work well with some grain.
Be sure to work on a duplicate (Ctrl+D) of your image
because we'll need access to the original ungrainy image a little
farther on...
|
|
|
Double-click on the foreground color icon (the black square, see
right) in the GIMP toolbox to bring up the color selection
dialog. Dial in the color Red=128, Green=128, Blue=128 and
click OK; this should make the foreground icon a neutral gray,
as shown at right.
|
|
Bring up the Layers dialog (Ctrl+L) and click on the new layer
icon ( ). In the New Layer
dialog, name the new layer "Film Grain", select Foreground as
the fill color, and click OK.
You should see your image obscured by the new gray layer. In
the layer blending mode drop-down box of the Layers dialog (see
Layers dialog at right) select Overlay. Now you should see your
image again.
|
|
|
With the Film Grain layer selected in the Layers dialog, bring
up the Scatter HSV filter (Filters/Noise/Scatter HSV). This
filter will add a noise pattern to the neutral gray layer, which
will overlay on to the image below.
Here's a not-too-technical interpretation of the filter
parameters for the purpose of creating grain:
Play with the parameters until you've got an interesting grain
pattern in the preview window of the filter, then click OK.
When the filter finishes you should see your image take on a
grain pattern.
If you don't like the look, Undo (Ctrl+Z) and reapply the filter
with different settings (Shift+Alt+F). Don't worry too much if
the grain seems a little too noticable, because the next step
will soften it.
|
|
|
Optionally, apply a bit of gaussian blur (Filters/Blur/IIR Gaussian
Blur) to smooth the grain a little. Note that if you use
anything other than a very small blur radius you will counteract
the effect of adding the grain in the first place, and you'll
end up with a noisy, but not noticably grainy
image...so go easy.
A value between 1-3 should be sufficient, and then only if
you used a high Value setting in the Scatter HSV filter.
If you like the grain the way it is, skip this step.
If you don't like the look after this filter finishes, Undo
(Ctrl+Z) and reapply the filter with different settings
(Shift+Alt+F).
Although you can stop at this step with good results, I
often like to go a couple steps further...
|
|
|
Normally, film grain tends to be most noticable in the midtones,
and much less so in the shadows and highlights. We can add a
layer mask to control how the grain pattern is applied to the
image to accomodate this observation.
Right-click on the Film Grain layer and select Add Layer
Mask. In the Add Mask Options dialog, choose White (Full
Opacity; Note: what you choose here doesn't actually matter,
we're going to paste over it anyway).
In the Layers dialog, click on (select) the Background layer.
Go up to the image window, select all and copy (Ctrl+A then
Ctrl+C). In the Layers dialog, click on the layer mask icon in
the Film Grain layer (the little white square). Then go back up
to the image window and paste (Ctrl+V)
In the Layers dialog, click the Anchor button to anchor the
pasted image into the layer mask.
|
|
|
With the layer mask still selected (it should be, if you just
pasted into it), bring up the Curves dialog by right-clicking in
the image window and selecting Image/Colors/Curves. Click to
add a control point in the middle of the linear graph. Then grab
the right (upper) endpoint and drag it down to the lower right
bottom as shown at right. What you are doing is
"half-inverting" the layer mask: making all highlights
into shadows so that the midtones are the brightest part of the
image. If you're grain seems too subdued, you may want to drag
the midpoint up a bit to raise the brightness of the midtones;
watch the image window as you are adjusting this to see the
effect on the grain. When you're all done click OK.
To more clearly see the effect of the layer mask, hold the
Control key and click on the layer mask icon in the Layers
dialog: a little red outline should display around the icon and
the image window will change to show the blend without the
effect of the layer mask. Control-click the icon again to
toggle the effect of the mask back on. With the layer mask
active, you should see a subtle difference in the way the grain
shows up in the shadows and highlights and overall the grain is
more subdued than without the mask.
You may prefer to do the grain blurring step last. Just be sure
to click on the grain thumbnail in the Layers dialog before you
apply the filter; otherwise you will just be blurring the layer
mask!
If you want to do further image editing on the image it might be
a good idea to save your work under a new name at this point, or
duplicate the image (Ctrl+D) and flatten it (RC/Layers/Flatten
Image). If the GIMP had adjustment layers, we'd just create one
of those to continue with further enhancements, but lacking that
it's a good idea to give yourself a "checkpointed" result that
you can start over with if further edits go awry. You can
experiment with changing the hue and saturation, punch up the
contrast with levels and curves, or do any other necessary edits
at this point on the flattened version.
|
|
).
Text and/or images are available for personal or commercial use
under certain conditions.
