Photoshop Techniques
Part I
Selection & Interpretation
By Gordon Osmundson
Presented to the Center for Railroad Photography and Art 2011 Conversations on Photography conference
2. How the Eye Sees
P Very high exposure latitude
P Ability to see into shadows
P A large part of the human brain is devoted to
analyzing input from the eyes and from this
constructing a three dimensional reality
P This ability also allows us to recognize the
content of photographs
3. Two Kinds of Black
P The Color Black
P The Absence of Light Black
18. Expose for the Shadows
We expose what we want as a detailed shadow
two stops down from middle gray or Zone V
19. Expose for the Shadows
We expose what we want as a detailed shadow
two stops down from middle gray or Zone V
This gives us an exposure for Zone III
20. Note that I use a
one degree spot
meter to determine
these exposures
21. Develop for the Highlights our
By adjusting
development
times we can
change the
value of our
highlights
22. Develop for the Highlights our
By adjusting
development
times we can
change the
value of our
highlights
23. Develop for the Highlights
P Typically we would want to move our
highlights up or down, plus or minus to keep
a detailed highlight in Zone VII
P If we have, say, a five stop difference
between our shadows and highlights and we
want it to be four stops we give Normal
Minus One (N-1) development.
P If we had a three stop difference and wanted
four we would give N+1 development, etc.
P You need to run tests of your camera, lens,
24. Response Curve for Silver Gelatin Paper
Shoulder
D-Max or
Maximum Black
Straight Line Section
Paper
White
Toe Note that there is no such thing as
latitude with printing paper. We use
Printable the entire printable range of the
Range paper.
25. How Film Sees
1 2 4 8 16 32 64 128 256 512 1024
Each zone represents a doubling of light
26. Clipping Point
Response Curve for Jpeg
Straight Line
Note that there is no latitude in digital
Clipping Point capture
27. A Bit about Bits and bytes
P Commuter machine language is binary, that
is it is based on Zero and One giving two
possible states, 0 and 1. This is known as a
bit.
P With two bits we have four states; 0-0, 0-1, 1-
0 and 1,1
P With three bits we have eight states; 0-0-0,
0-0-1, 0-1-0, 1-0-0, 0-1-1, 1-0-1, 1-1-0 and 1-
1-1
P With four bits we have 16 states, etc.
29. A Bit about Bits and bytes
8 Bit vs. 16 Bit
P An 8-bit gray tone Jpeg has 256 shades of
Gray
P A 16-bit gray tone Tiff file has 65536 shades
of Gray
P The 16-bit file takes up only twice the storage
space of an 8-bit file, but has 256 times as
much information
P 256 Shades of gray actually produces a
pretty good print and is fine for use on the
web
31. Response Curve for CameraClipping Point
RAW
Jpeg
Camera RAW
Clipping Point
32. Translation of Camera RAW
P The typical digital camera uses 12 bit
capture, that is they have 4,096 shades of
gray.
P Some newer high end digital cameras use 14
bit capture or 16,384 shades of gray.
P The camera’s microprocessor converts
camera RAW’s curve into a straight line 8 bit
jpeg.
P Photoshop does the same thing, but it also
allows you to convert to a 16 bit TIFF file,
35. Using the Histogram in Camera
P Use the histogram to insure that you are not
clipping your image.
P The higher end cameras will give you a
histogram on the viewing screen and others
can be set to display a histogram of the
image that you just took.
P In either case adjust your exposure + or - so
that you are not clipping either the shadows
or highlights.
P It is common to have clouds or bright
36. What I do
Digital Capture
P For digital capture, to minimize digital noise, I
set may camera to a ASA of 80 or 100 and
always shoot in camera RAW.
P I then convert these files into 16 bitt TIFF
files.
P I process the color images in Photoshop and
save them.
P I then convert them to B&W and further
process them and save the results as a new
B&W Tiff file.
37. What I do
Scanned Negatives
P I scan my 4x5 negatives with an Epson 4990
desktop scanner set at 1200 dpi to create a
16 bit Tiff file. You can see the film’s grain in
these scans.
P Using the scanner’s histogram, I adjust each
scan so that I get the maximum contrast
possible without clipping.
P I may also use the tone correction feature if
the image appears unusually dark or light.
P Other settings I use are the unsharp mask
38.
39. What I do
Scanned Slides
P I scan my 35mm slides with an Epson 4990
desktop scanner set at 4800 dpi to create a
16 bit Tiff file.
P Using the scanner’s histogram, I adjust each
scan so that I get the maximum contrast
possible without clipping.
P I may also use the tone correction feature if
the image appears unusually dark or light.
P Other setting I use are the unsharp mask
filter and dust removal.
40. Now into Photoshop
First step is to rotate (if needed), trim, align, correct
perspective, clean and sharpen our images.
P Rotate the image if vertical or horizontal
alignment needs to be changed. [Image >
Rotate Canvas> . . . ]
P Trim anything extraneous in the scan by
selecting the desired area using the
Rectangular Marque Tool.
P Use [Edit > Copy] to save. Open a new file
[File > New], select OK in the diolog box,
Paste your selection into the new window.
[Edit > Paste]<Crosshead 8444>
41. Aligment
P One of the reasons that I like to use a view
camera is that it allows you to control
aligment & perspective in camera. Very
useful in the days of the traditional darkroom,
but still nice to do even with Photoshop.
P Many hand held images can benifit from
aligment & perspective correction. <Cobre
Photo>
P Turn on Grid. [View > Show > Grid]
P Select All. [Select > All]
42.
43. Perspective
P If the horizon is in the center of the image,
there should be no need for perspective
adjustments.
P If the camera was pointed up (or down) there
will be vertical perspective convergence.
P To correct, turn on Grid. [View > Show >
Grid]
P Select All. [Select > All]
P Now pick a vertical line at or near the edge of
44. Perspective, Cont.
P If important items in your composition fall off
the edge of the image as you adjust
perspective, the canvas size my need to be
enlarged.
P To enlarge the canvas, select Enlarge
canvas. [Image > Canvas Size]
P Adjust Box size by inserting new dimensions.
P Click OK.
P We will look at how to repair any left over
45. Perspective Continued
P To enlage the canvas select Enlarge canvas.
[Image > Canvas Size]
P Delete bottom arrow in dialog box.
P Adjust note size by
Also, you willBox that there inserting new dimensions.
is some vertical distortion
P Click OK.
when you adjust the
perspective. You can fix [Select > All]
P Now Select All. this
by stretching the image at the
P This distort to adjust the aspect ratio. [Edit >
top.Use also requires
changing the canvas size.
Transform > Distort]
P Pull the top to adjust the aspect ratio.
46.
47. Fixing Flaws
Cleaning, with the Healing Brush
P With Slides and Negatives we need to
remove dust and other imperfections. This is
done using the Spot Healing Brush Tool and
the Patch Tool.
P With my files, I like to zoom in to 50%. Any
flaws that this doesn’t reveal will likely not
show in your prints.
P Use Ctrl + and Ctrl - to zoom in and out. Ctrl
0 to fit the image to the screen.
P Note that the Spot Healing Brush Tool works
48. Fixing Flaws
Repairs with the Patch tool
P While the Spot Healing Brush Tool works
well in areas of continuos tone, flaws on
edges or items in textured areas that we
want to remove can be addressed with the
patch tool.
P The Patch Tool also works well with flaws on
edges. <Sierra Double Header>
P You can also use it to remove unwanted
things from the image. <2472 @ Farwell>
49.
50. Sharpening
P Almost every image can benefit from some
sharpening.
P I found that scanned prints were not quite as
sharp as the originals, but with sharpening
they were sharper.
P Sharpening works by detecting edges and
increasing the contrast at the edge.
P Some people sharpen specifically for the size
of the print, but I haven’t found this
necessary.
51. Sharpening, cont.
P Photoshop offers several sharpening tools.
The one I use most is called unsharp
masking. [Filter > Sharpen > Unsharp Mask]
P With the size files that I like to work with,
settings of 50 to 100 in Amount seem to work
well with most images. I leave Radius at 1
and Threshhold at 0.
P If your image is slightly out of focus, it can
sometimes be made acceptable by using a
higher number in Amount.
52. Conclusion to Part I
Before we take a break . . .
P So far, except for cropping, we haven’t really
done anything to interpret our images.
P What we have done is really all pretty
mechanical.
P At this point I like to save my file in a folder
for Cleaned, Cropped, Rotated, Sharpened
and Corrected images.
P We’ve done a lot of work and may want to
come back to this point if we later want to
change, improve, whatever our later
