Part 1- Initial backup and sharpening
After you have captured those wondrous moments in time
called images you rush home to download and save the "keepers" to
your hard drive. Only later when you are ready to work
with the images you discover that a virus has obliterated
your hard disk! Back up your files as soon as you pull
the raw images out of the camera. This keeps an unaltered
copy for later use. Label and store these images away into
a long term storage container. I generally buy several
200 CD jackets when they go on sale at W*lm*rt or T*rg*t
(that's all they get until they pay for endorsements) for
around $15 each. Be descriptive in your labels I write
the date, location, numbers of files I index these to a
spread sheet where I can add extensive comments about any
additional information (camera and settings), like any
particular photos I may need to reference later (PICT0023-
Pelican for postcard). Any good spreadsheet program will
let you sort and search your archives and content.
The next step is to duplicate the images again to a "working
folder" and begin the first level of correction.
Level 1 - Corrective Sharpening - Requires at least Photoshop
5. There's a lot of misunderstanding about when and how
to apply sharpening. I find it useful to break down sharpening
into three general categories: Corrective sharpening, which
compensates for blurring from either the camera or lens.
Creative sharpening, which you apply to a specific part
of an image and not another (eyes, but not Crows Feet).
Output sharpening, which is based on where you plan on
the image's final output destination (print or web, postcard
or billboard). In this installment We are going to cover
Capture sharpening and neutral color correction (this assumes
you want to get rid of a color cast).
I have found after working with several digital cameras
that the CCDs suffer from some loss in contrast which holds
the same from photo to photo, some cameras more than others
especially in cameras that are more than 3 years old. CCD
technology has changed significantly over time and the
new sensors far exceed their predecessors of even 18 months
ago. None the less, even the newest technology still benefits
from some sharpening. The following procedure can and should
be recorded as an action script as this corrects inherent
and unique and reoccurring issues with your camera, if
you use different cameras you should create a separate
script with unique settings for each.
For this tutorial you will need at least Photoshop 5 and
an uncorrected photo with a good range of textures and
contrasts and in need of some color correction (or you
can download the sample
photo from here). The sample photo
is of some granite rocks at John's Pass. There is plenty
of texture in the photo but by comparison to what was actually
there the image seems flat and boring. Part of the trick
to sharpening an image is to avoid producing color halos
around objects in the picture. Even a light amount of the
Unsharp Mask filter will cause some haloing of the colors
in the photo. To reduce haloing we will remove the colors
from the problem.
Step 1) Convert the file to LAB color space (Image>Mode>LAB
Color). This will separate the color information from the
light and dark information. LAB creates color channels
A and B and a separate lightness channel (fig 1).
Step 2) In the Channels Pallet choose the lightness channel
(fig.2) and apply a light amount of the unsharpen mask(Filters>Sharpen>Unsharpen
Mask) with starting settings of Amount=100% , Radius=1.0
,Threshold=0. Click apply (fig.3). and switch back to RGB
mode (Image>Mode>RGB). The channels pallet will switch
back to RGB (fig.4).
Experiment with the settings till you are satisfied with
the result, try different "Amount" settings of
less than 100% to reduce the lighter halo, more than 100%
to increase texture.
Step 3) Save the file as a PSD and proceed to color correction.
This tutorial assumes that you have already color corrected
your monitor for use with Photoshop. The first problem
in color correction is in Photoshop's own default Eyedropper
settings that we must correct first. In nature true black
and white are never pure black and pure white but a mixture
of the spectrum. By adjusting Photoshop's Eyedropper white
point, black point and gray point we will get a more realistic
color correction. Open the sample image from the previous
tutorial.
Step 1) Change the setting of the eyedropper tool from
1x1 pixel to 3x3 pixel average sample by selecting the
Eyedropper from the Tool Bar and then up in the Options
Bar change the setting from "Point Sample" to "3x3
Average" (fig. 5). Single pixel sampling is inaccurate
for use with most photos.
Step 2) Open the "Curves Pallet" (command or
control M). Start by dbl clicking on the black filled eyedropper
on the bottom left of the "Curves Pallet" (fig.
6). A color picker box will open enter 10 in the R, G
and B
boxes.
Click OK in the Color Picker box (fig. 7). Now dbl click
on the white eyedropper in the "Curves Pallet" as
before enter these settings R, G and B boxes 244 and click "OK" as
before. Now the dbl click the gray eyedropper and enter
settings 133 in the R, G, and B boxes and click "OK".
Click "OK" in the "Curves Pallet" a
message box, "Save the new target colors as defaults?" click "Yes" (fig.
8). Now we are ready to begin.
Before we begin the next step I find some quick clarification
is in order. We will be using the "Threshold" adjustment
layers but not ever creating them (not clicking OK) and
once you select the "Color Sampler" tool do not
select a different tool.
Step 3) Go to the "Layers Pallet" and create
a "Threshold" adjustment layer (fig. 9, 10, 11).
Move the slider all the way to the left so that the image
turns
completely
white. Slowly move the slider back to the right till the
first small areas begin to turn black. These are your whitest
points. Click the "Eyedropper"tool and
set your first target in the first bit of black you see
that
is
at least 3x3 pixels wide by clicking the area with the "eyedropper" tool
while pressing the shift key.This will leave a numbered
target marker. Run the slider all the way to the right
to make the image totally black. Slowly move the slider
back to the left till the first small areas begin to turn
white. These are your blackest points. Set your second
target in the first bit of white you see that is at least
3x3 pixels wide. Click "CANCEL" in the threshold
adjustment box. You will still see the previous two targets
you made with the "Sampler Tool".
Now for the neutral gray (without guessing!). In the "Layers
Pallet" create a new empty layer above the background
layer. Fill this layer with 50% gray (Edit>Fill and
choose 50% gray from the "Fill with" drop down
and opacity of 100%). Click "OK". In the "Layers
Pallet", set the "Blend Mode" of the new
layer to "Difference". Again, create a "Threshold" adjustment
layer. Drag the slider to the left till the image is all
black, slide to the left till the first white begins to
show. Place your third color sampler target in the first
3x3 white area that shows this will be the true mid-tone
gray area in your photo. Click "CANCEL" to abort
the adjustment layer then delete the gray layer you created,
you should see all 3 targets on your photo.
Step 4 ) Now the corrections. Now open the "Curves
Pallet" (ctrl/cmd-M). Select the white eyedropper
from the lower left of the "Curves Pallet" then
carefully click on the first target (the White Point) you
create in the previous steps. Then choose the black eyedropper
and click on the second target you created from before
(the black point) and finally the gray eyedropper to the
third target.
Stay tuned for further tutorials on cosmetic sharpening
and other useful special effects.
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