Ever seen a great toned B&W image and wished you could tone your
images that way? Wondering how difficult it is to do your own
sepia/platinum/silver/cyanotype/duotones/tritones/quadtones/<insert
your favorite> toning in the digital darkroom?
At Photoshop for
Photographers (click in the left column on "Black and White" and
then on "Copy a Tone"), Thomas Niemann describes an excellent technique
for "mimicking" tonings found in existing images and applying them to
your own images using Curves . Of course you can reproduce this procedure
(with only slight variations) in the GIMP, but fortunately for GIMP
users, there is a much, much easier way!
The GIMP has a great filter called Sample Colorize. This
versatile filter allows you to "rip" (sample) the colors used in an
image and apply them to a grayscale image. It is particularly effective
on extracting tonings from images where there is only a single tone
corresponding to a particular luminosity level. In other words, most
toned B&W images, but also most duotones, tritones, quadtones, etc.
In this tutorial I'll show you how to use this filter to tone your
B&W images with a wide variety of tonings and to rip your own
tonings.
Move your cursor focus back to the image to be toned and run
the Sample Colorize filter (Filters/Colors/Map/Sample Colorize).
In the sample side options, choose the appropriate toning image
in the drop down box. You probably want to keep the
"Smooth Samplecolors" checkbox checked and the "Use subcolors"
unchecked. In the destination side options, you probably want
to keep the "Hold Intensity" checked. See the discussion in
the Tips section below for some information on these.
Click "Get Sample Colors" to get the sample colors into a
the destination preview.
If you want to adjust the luminosity (brightness or darkness) of
the destination image then uncheck the "Original Intensity"
option and adjust the In Level sliders accordingly (if you try
to run an ordinary Levels command after the toning you may shift
the toning color in unexpected ways). If Original Intensity is
checked, then adjusting the In Level sliders just changes the
distribution of sample colors without affecting luminosity.
Play with this option a bit and you'll see what I mean.
After adjusting settings to your liking, click "Apply" to tone
the actual image. Sit back and drink some coffee. On my Athlon
1800+/1.5GB the filter took 78 seconds to run on a 3000x2000
pixel image.
Discussion of Sample Colorize filter options
Use Subcolors
The "Use Subcolors" option only comes into play if you are
mapping a sample image that has more than one color for the same
luminosity level. In this case the filter has to decide which
color gets mapped to the same value point in the destination.
This option determines how the colors are sampled to affect the
corresponding destination values. If "Use Subcolors" is off, then
the dominant color is used (the one with the most pixels with that
value); if the option is checked, then the colors are sampled in a
weighted fashion.
For example, suppose you are trying to sample a
color photograph that for a particular value in the range 0-255,
say 101, there are four distinct colors with that overall value,
each in different amounts. Suppose that the percentages for this
value break down as: 50% of the pixels of that value are the first
color, 30% of them are the 2nd color, 18% of are the 3rd and 2% of a
fourth. Now our sample gradients that we are mapping to
have one column for each value, from 0 to 255, and each column is
100 pixels high. So for this value, if "Use Subcolors" is
checked, the 101th column will have 50 pixels of the first color,
30 pixels of the 2nd, 18 of the 3rd and 2 of the last. If the
option is not checked, all of the pixels in column 101 will be of
the color that has the 50% share.
If you are sampling a typical toned B&W image this is not
an issue, and the setting doesn't really matter, since the majority of the
pixels in any column would end up being the predominant color in
that level. However, I would recommend unchecking the option
in this case to avoid contaminating the sample with stray pixels. On the
other hand, if your intent is to capture the toning of a
photograph that does make use of multiple colors within the same
brightness level, you'll want to select this option. Please
realize, however, that the sampling will only be approximate: e.g. if
you tried to recolor a desaturated version of the original sampled image
with your new gradient sample it would not be able to reproduce the
original exactly, and in fact you may be lucky to even get close to it.
I've found that it can often do a decent job though. Visit the samples collection to see an example
of what I am talking about.
Smooth Samplecolors
The "Smooth Samplecolors" option allows the filter to interpolate
colors for missing values in the sample image, resulting in
smoother gradations of toning in the destination. Posterization
might result if you don't check this option. There may be
situations in which you do not want to check this option (odd,
non-linear effect tonings come to mind), but I think it is a good idea
in most cases to select it.
Hold Intensity
According to the GIMP Users
Manual, if the Hold Intensity option is unchecked then
colorization is accomplished by mapping the color in a
semi-transparent layer over the image, rather than by "true
colorization". I am not sure what they mean by this. I have
experimented a bit with this option and it doesn't seem to make
much difference to the result. If someone can clarify this option
for me please drop me a note.
See the manual for a discussion of other filter options/controls
not discussed here.
Tips
The Sample Colorize filter also allows you to just work on a
selection instead of the whole image. This is handy if you want
to tint different parts of the image separately or use different
tonings.
Another very similar toning approach uses gradients.
Open the Gradients selection dialog and pick an interesting
gradient. Then run Filters/Colors/Map/Gradient Map. You can
create new gradients using the Gradient Editor.
You can also choose gradients as the source in the Sample Colorize
filter. This must work nearly identically to Gradient Map except
that you have the extra options for subsampling, etc.
The real benefit to GIMP users in Niemann's tutorial is
his collection of classic tones (visit Photoshop for Photographers
and click on "Black and White" and then "Classic Tones"). These are
sampled here, along with some others. You can download a particular
tone by shift-clicking on it's gradient; save it and use it to tone your
own images.
Note that the displayed gradient is not the same as the sample
gradient! i.e. don't right-click to save the gradient with the
text on it, shift-click to save the link target!
If the image has a border, caption/text, etc. that is not
toned, be sure to crop that part off so as not to
contaminate the tone sample.
For best results, try to find a toned image that has a complete
range of tones, from very dark to very light.
In the grayscale gradient, run the Sample Colorize filter
(Filters/Colors/Map/Sample Colorize). Choose the image you want
to copy the tone from in the sample side.
If the image to be sampled has more than one color per
luminosity value (e.g. a "color" photograph as opposed to a
toned B&W photograph), then be sure to check the
"Use Subcolors" option.
Click "Get Sample Colors". When that has completed, click
"Apply"; the grayscale gradient should take on the toning of the
sample image.
Now save your gradient as a new toning sample, preferably as a
PNG or TIFF.
If you find a great toning image somewhere or come up with
one a great tone and you'd like to see it added to the
toning samples collection, please
send me the
gradient as prepared above. If you have a particular name in mind for
the sample send it along in the email message body.
p.s. I am also looking for traditionally (wet darkroom) toned images to
use in verifying the authenticity of these "classic" tonings. If you have
such an image, I would appreciate it if you could send me a small
digitized copy of the image; it need not be any bigger than 300-400
pixels in any dimension (just big enough to contain the full range of
color values in the image). Alternatively, if you see one on the web,
please point it out. I am currently looking for good examples of any
interesting historical tonings.
).
Text and/or images are available for personal or commercial use
under certain conditions.
