Effective Digital Imaging - Wake Forest University

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29 Οκτ 2013 (πριν από 3 χρόνια και 7 μήνες)

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Effective Digital Imaging

using


Basic Composition

and

Adobe Photoshop

Paul S. Marley

Instructional Technology Specialist

Department of Art

Wake Forest University

336.758.4803

marleyps@wfu.edu


http://www.wfu.edu/~marleyps/


Basic Composition



The Rule of Thirds


http://www.ruleofthirds.com

(David Freidman)


Photo Tips by Kodak

http://www.kodak.com/eknec/PageQuerier.jhtml?pq
-
path=2/3/38/315/332&pq
-
locale=en_US

>>Left to Right>>

Our eyes are trained to move from left to
right so the flow of your image should
“move” in this direction to make viewing
your subject feel natural.

Images can be VERTICAL


If an image isn’t working in the horizontal
view try the vertical

Adobe Photoshop


Curves


Levels


Image Size


Sharpening

Curves (Ctrl + M)


Curves is used to manipulate the color of
an image.


Common tasks in Curves are:


1.
Balance image’s color

2.
Enhance Brightness and Contrast

The Auto (correction) button
can be a good place to start
on a less than perfect
image.

The Info palette should always be referenced while
using curves. It shows the R (red), G (green), and


B (blue) values for any area in the image.


It will also show you values in the C (cyan)

M (magenta), Y (yellow) and K (black) for those
same areas. These four values are used by the
Offset Printing Industry.


You can see the X and Y coordinates of any desired
pixel within the image and get the W (width) and


H (height) when using the Measure Tool.

Select Eyedropper Tool (I), set sample size to 3X3


then place the cursor somewhere on the image to read values


Info reference markers can be placed anywhere in the image. Select the
Eyedropper Tool, press the Shift key and click the mouse while over the
area you want to mark. The values of the area will display at the bottom of
the info palette with a marker number. These markers will
not

print and can
be removed by clicking and holding on them while in the Eyedropper Tool
and dragging them out of the image area.

Curves allows you to manipulate
the colors individually or
simultaneously.

The values you are trying to reach
are:

Highlight (white)


240

Shadow (black)


25

Info marker should be placed in
these areas where detail can be
seen.

Total white


255

Total Black


0


The Curve of the image is set up
with the bottom left being the
Shadow point, the middle being
the Midtone and the top being
the Highlight.

To control a point on the curve,
click and hold it with the mouse.

Move the Shadow point to the
right to increase darkness. Move
it up to decrease darkness.

Move the Midtone up and the
image lightens down and it
darkens.

Move the Highlight to the left to
brighten and down to darken.

The image will show the change as it is made.

As you move the Curve you will notice the values are now indicated as:

208/191

The value left of the backslash is the original value while the other is the new
value.

After you have made the color
correction desired you can
Save the changes to be used
on other images that may
require the same adjustments.
Click on the
Save

button
BEFORE

you click
OK.
An
.acv file will be generated and
you will be prompted to name
and file it.

To apply the adjustments to
another image, open it go to
Curves and click on Load then
retrieve the .acv file.

Click
OK

to finish your manipulation. A
Save As

at this point would be advisable.

Things to watch:

1.
Major corrections may have to be made in multiple moves instead
of all at once.

2.
Digital photographs don’t hold up well to extreme correction.
Artifacting (small random areas of color anomalies) will likely occur,
especially when brightening a dark image. Make initial exposures
as good as possible.

3.
Place a Grayscale in image if possible for more accurate
corrections.

You now see the Adjustment Layer in the
Layer Palette.

Levels (Ctrl + L)

Levels is another means of color correction that uses a visual
interface instead of a graphical. A Histogram of the image’s color
spectrum is displayed for reference and manipulation.

Photoshop often gives users multiple ways to achieve the same
results. Curves vs Levels is a great example of this point.

Also use the Adjustment Layer for this as you did in Curves

Info reference markers are placed using the same method as
described for Curves and serve the same purpose. The same ability to
alter individual colors is also present, as is save/load of adjustment
files.

Select the color and adjust by moving the slider that represents the part of
the spectrum you want to change. Highlight/Midtone/Shadow are indicated
by color of the slider.

Images Size

The first rule of image size is: Know the end result of your image be it print,
multimedia or web.

The second rule is always capture as big a file as you can manage easily
(usually 300ppi) because you can always decrease images size. Increasing
an images size will NOT improve its quailty.



Image size is determined by


W (width)



H (height)


Resolution (pixels per inch, ppi)


Commonly used resolutions: (in ppi and file type)



Printing = 300 or + (.tif)



Powerpoint = 150


72 (.tif or .bmp)



Web = 72 (.jpg)



From the pull
-
down
menu:

Image


Image Size…

If you are changing dimensions then
make sure Constrain Proportions is
checked to avoid image distortions.

The Link symbol will appear
connecting the Width and Height

To change Resolution make sure the Resample Image is
checked. If it is not and you alter the ppi the Width and
Height dimensions will change proportionally to the
change in ppi, leaving your image “size” unchanged.

FYI

Side dimensions for use by Biomeds Film recorder:


4096 X 2730 pixels


Save as .jpg w/10 compression


send file by Upload page:


http://www.wfubmc.edu/biomed/pc_upload.html


then fill out order form:


http://www.wfubmc.edu/biomed/order/slides.html


(will need budget code or credit card number)


One or two day return

about $5 per slide

Sharpening:


Visit the section on scanning in my WFU website

http://www.wfu.edu/~marleyps/ps_stuff.htm

“Scanning a new image “

The End…?