Unit One - Photos
Over the last two decades digital
cameras have gone from being an item
that only scientific research groups and the government could afford,
an item that most people have or know someone who has. They have
gotten so small and portable that they are embedded in most modern cell
phones. With the upswing of digital cameras and digital
has come the ability, which wasn't readily available with photographs
in the past, to modify them after they are captured. This has for
first time enabled non-professionals to improve the quality of their
photos using cheap and simple tools to the point that they can match
what is done by many professionals.
For this unit we will learn some basics
about digital images and photos. We will then learn how to use
photo editing software to improve photos. For this we will
primarily be using the GNU Image Manipulation Program (Gimp), but we
will also look at the tools available in Adobe's
Photoshop program to see how to do the same things, where available.
If you don't already have the GIMP installed on your computer, see the page
on downloading free software.
Section 1 - Introduction
Section 2 - File Types
Section 3 - The Gimp
Section 4 - Basic Manipulations
Section 5 - Red Eye Correction
Section 6 - Selection and Layers
Section 7 - Lighting
Section 8 - Touchup
Section 9 - Photoshop
Pixel - One dot in the image, composed
of Red Green and Blue components (and possibly Alpha for indicating if it has
Dimensions - The size of the picture,
indicated by Width X Height.
Raster - An image made up of pixels
arranged in a grid measured by the dimensions.
Resolution - How fine of detail you can
see in a picture, related to the number of pixels in an image.
Megapixels - The number of pixels in
the image, in millions.
Aspect Ratio - The ratio of the width
of the image to the height of the image. For photographs this is usually 4:3.
Landscape Orientation - When a photo is
in the direction where it is wider than it is tall (4:3)
Portrait Orientation - When a photo is
in the direction where it is taller than it is wide (3:4)
Channel - The different
Lossless Compression - Storing a file
so that it can be perfectly re-created
Lossy Compression - Storing a file so
that it is smaller, but loses some amount of detail
Undo - The ability to go back to the
state of a file before you made a previous change to it
Rotate - Change the orientation of the
Crop - Cut off the an area around the
Re-Size - Change the number of pixels
that the image is without cutting off any parts of the image.
Scale - Another word for re-sizing,
when you change how large the image is.
Red Eye - A artifact caused by the
flash in a camera that causes the eyes of a subject to look unnaturally red.
Selection - An area of the image that
has been designated to be used for something else. It can be copied to the
clipboard or can have an action directly applied to it.
- A point on an irregular selection that defines the boundary of the
selection. These can be modified or moved to change the selection.
- One of possibly many levels of data in the image, these are all
applied to the image simultaneously, but in order, to produce the final
- The ability of pixels to be seen through to the next layer. The channel that
stores the data for this is called the "Alpha" channel.
- When too much light has been absorbed by the camera's sensor. This causes
the colors in the image to look washed out.
- When not enough light has been absorbed by the camera's sensor. This causes
the image to look dark.
- The amount of light that the image has. On an absolute level (for 24-bit
images) the closer the pixels are to 255 the brighter the image is.
- The amount of variation between pixels in an image. If many of the pixels are
close to the maximum value and another large group is close to the minimum
value, then the image is said to have high contrast.
- The amount of brightness (or a sepcific color) that pixels have.
- A graph that shows the number of pixels at each level in the image.
- When an image uses only black, white, and shades of gray instead of color.
- The shape of the tool that applies various effects (heal, erase, paint,
dodge, burn, and more) to an image.
- Increase the brightness of part of a photo.
- Decrease the brightness of part of a photo.
Other Photo Editing Tools
Picasa -- Photo manager built and distributed by google. It
is more for storing photo collections, and managing them online
and offlline, but also has some photo editing ability, like cropping,
redeye removal and more. Available for Linux, Windows and Mac. -
Paint.NET -- Similar, but less powerful than Gimp and
Photoshop. Only available for Windows, but is free, libre, and open
source software. - http://www.getpaint.net/
Histogram - A graph that shows the number of pixels
Corel Paint Shop Photo Pro -- Almost as powerful as Gimp
and Photoshop, but a substantially different interface from them. -
Microsoft Paint -- Comes built in with windows, but is
very basic. Even things like cropping and re-sizing are very
difficult. It is usable if you want to add a little text to an
image, or draw over something so that others can't see it (like
blanking out a screen name or IP address in a screenshot), but not
much beyond that.
Microsoft Photo Editor or Photo Manager -- Tools
from Microsoft that come with Microsoft Office. Useful for basic
editing, such as cropping and re-sizing.
ImageMagick -- A command line based tool (there are also
various graphical user interfaces for it) that instead of editing an
image by click on it edits the image by specifying commands that can
be done to it (e.g. -resize 30%, -crop 120x120, convert image.jpg
image.png and lots more). This is really great if you have a lot of
images and want to do the same thing to all of them. For instance
you can easily resize hundreds of images in a few seconds instead of
opening them up in the Gimp and resizing them one by one. Image magic
is free, libre, and open source software and runs on Linux, Windows,
and Mac. - http://www.imagemagick.org/
Hugin -- This is a tool that
will create a very high resolution panoramic photography by stitching
together multiple, overlapping photographs. When you have a
large, stationary (at least for a minute) scene like mountains, lakes,
etc., you can take several pictures where each one overlaps ~1/3 of the
one next to it. Then feed all these images into Hugin, and it
will give you an output image that combines all of the input images
into one. http://hugin.sourceforge.net/
UFRaw -- Some, more
advanced, cameras will allow you to get your images out of them in a
format generally called "Raw". This keeps any of the data that
might have been lost in the JPEG compression, as well as more data that
came from the sensors about the image. This extra data is useful
for professionals, as it allows them better control over
color/brightness corrections. UFRaw is a program that will work
with this raw images, it also has a plugin for GIMP that will let you
work with them in the GIMP. http://ufraw.sourceforge.net/
FSpot -- A photo manager,
similar to Picasa, but open source (unfortunately, only runs under
Shotwell -- A photo manager,
similar to Picasa, but open source (unfortunately, only runs under
Photos and File Types
1- Select all of the following image resolutions that are in a 4:3
ratio? (A typical landscape picture)
2- How many color channels does a 24-bit photograph have?
3- What color to you get from a pixel that has the following components
(8-bit) Red:200, Green:50, Blue:200 ?
4- What pixel components (8-bit) make the color yellow?
A) R:255 G:0
B) R:200 G:200
C) R:255 G:255 B:
D) R:100 G:50 B: 220
5- What is the un-compressed size of a 24-bit, 1600x1200 photo?
D) 576 KB
6- Lossless images are good for websites where it is important to
have quick downloads.
7- Lossless images are good for editing images, where it is
important to not lose any quality while editing.
8- Which image format is most used by consumer cameras?
These three images are quite
similar to the original, they can all be
rotated, cropped, and re-sized.
Red Eye Reduction
These images are all examples of red eye that can be removed by
selecting the eyes and running the red eye removal tool on them.
Seleccion and Layers
Here are some more pairs of images you can try this out with.
Here are some more examples of complex images with areas over and under
Here are some more faces with some small imperfections to try the tools
For the final project in this unit, you will need to go out onto the
internet and find two (or more) seperate photos that can be combined
together. This should be similar to the section on selection and
layers. However, you will receive more points if the images
require the use of other techniques that we have gone over such as
changes to lighting or rotation.
One great example you would be free to use: A picture of people
at a party, and another picture of a person dancing. Use
selection tools to copy the dancing person into the party
picture. Then use the light tools to match the lighting of the
dance with the lighting in the party. Finally, use the
corrections tools to make everyone at the party look their very
Before starting work on the editing of the images, your concept should
be submitted for review. It should include:
- The attribution line for each of the images being used.
- A written description of what operations you plan to perform on
these images, listed out step-by-step.
When you have completed your project, you need to submit it for
grading. Please include:
- The final image.
- The attribution line for each of your sources.
- A written description of what operations you performed to get to
the final image, listed out step-by-step.