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, to an item that most people have or know someone who has. They have even gotten so small and portable that they are embedded in most modern cell phones. With the upswing of digital cameras and digital photographs has come the ability, which wasn't readily available with photographs in the past, to modify them after they are captured. This has for the 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

Vocabulary

Pixel - One dot in the image, composed of Red Green and Blue components (and possibly Alpha for indicating if it has transparency)
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 red-green-blue-alpha components
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 image.
Crop - Cut off the an area around the image.
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.
Node - A point on an irregular selection that defines the boundary of the selection. These can be modified or moved to change the selection.
Layer - 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 image.
Transparency - 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.
Overexposed - When too much light has been absorbed by the camera's sensor. This causes the colors in the image to look washed out.
Underexposed - When not enough light has been absorbed by the camera's sensor. This causes the image to look dark.
Brightness - 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.
Contrast - 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.
Levels - The amount of brightness (or a sepcific color) that pixels have.
Histogram - A graph that shows the number of pixels at each level in the image.
Grayscale - When an image uses only black, white, and shades of gray instead of color.
Brush - The shape of the tool that applies various effects (heal, erase, paint, dodge, burn, and more) to an image.
Dodge - Increase the brightness of part of a photo.
Burn - 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. - http://picasa.google.com

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. - http://www.corel.com/servlet/Satellite/us/en/Product/1208716806081

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 linux). http://f-spot.org/

Shotwell -- A photo manager, similar to Picasa, but open source (unfortunately, only runs under linux). http://yorba.org/shotwell/

Exercises

Photos and File Types

1- Select all of the following image resolutions that are in a 4:3 ratio? (A typical landscape picture)

1920x1080	1600x1200	640x480	720x480	1280x720
1000x750	750x1000	720x640	1844x1383	1152x768
1024x600	3000x4000	1400x1050	8x6	4000x3000

2- How many color channels does a 24-bit photograph have?
A) 24                  B) 3                  C) 4                  D) 6

3- What color to you get from a pixel that has the following components (8-bit) Red:200, Green:50, Blue:200 ?
A) Orange                 B) Brown                 C) Purple                 D) Red

4- What pixel components (8-bit) make the color yellow?
A) R:255 G:0 B:255               B) R:200 G:200 B:200                 C) R:255 G:255 B: 0                 D) R:100 G:50 B: 220

5- What is the un-compressed size of a 24-bit, 1600x1200 photo?
A) 5,760 KB                B) 1,920,000 B                C) 1,024 MB                D) 576 KB

6- Lossless images are good for websites where it is important to have quick downloads.
True False

7- Lossless images are good for editing images, where it is important to not lose any quality while editing.
True False

8- Which image format is most used by consumer cameras?
A) JPEG B) PNG C) SVG D) TXT E) PSD

Basic Manipulation

These three images are quite similar to the original, they can all be rotated, cropped, and re-sized.
PhotoCrop-A-orig.jpg
PhotoCrop-B-orig.jpg
PhotoCrop-C-orig.jpg

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.

Redeye-A-orig.jpg
Redeye-B-orig.jpg
Redeye-C-orig.jpg

Seleccion and Layers

Here are some more pairs of images you can try this out with.

LayerBackground-A-orig.jpg
LayerForeground-A-orig.jpg

LayerBackground-B-orig.jpg
LayerForeground-B-orig.jpg

LayerBackground-C-orig.jpg
LayerForeground-C-orig.jpg

Lighting

Here are some more examples of complex images with areas over and under exposed.
Levels-A-orig.jpg
Levels-B-orig.jpg
Levels-C-orig.jpg

Touch Up

Here are some more faces with some small imperfections to try the tools out on.

Face-A-orig.jpg
Face-B-orig.jpg
Face-C-orig.jpg

Unit Project

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 best.

Preliminary Review

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.

Final Submission

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.