Goals
You are going to continue to work with
Photoshop CS3 one of the most sophisticated image
processing programs on the market.
- In this assignment you will learn how to do the following:
- Diffferentiate between bitmap and vector graphics
- Draw stright and curved paths using the Pen tool.
- Convert a path to a selection, and convert a selection to a path.
- Save paths.
- Draw and edit layer shapes.
- Draw custom layer shapes.
You may print a copy
of this assignment if you wish. However, we recommend that you access the assignment online as
there may be links on this document to other related
information, and the online version is always the most recent one, in case changes need to be made.
These instructions presume that you work on
this assignment on a Windows XP computer.
Note: Photoshop CS2 is available on a limited number
of computers on campus.
We strongly recommend that you work on the computers in the class lab(s).
For this assignment, and the remainder of the quarter, sections will be held
in Solís 105, north of the CogSci building
on Marshall campus.
The section times are at the same times as
posted previously on the web; only the location has changed.
See the class home page for
details about the sections.
Log In
If you are already logged in, you can skip ahead. Otherwise,
review the instructions in
a previous assignment
on how to log in.
And then log into your class file server.
Where to turn in
You should already have a hw2 folder in your
"home directory" folder in the "Class Resources" folder on the class file server
because of the previous parts of this assignment.
Save your work to that hw2 folder.
Bitmap vs. Vector Graphics
Bitmap images are:
- raster images, based on a grid of color pixels
- each pixel has a specific location and color value
To work with a bitmap image:
- you edit (modify) groups of pixels (or one pixel at a time)
rather than whole objects or shapes
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This photograph is a bitmap image.
The image below is a 1600% enlargement of a section of the photo above.
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The collection of bits form the image.
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The bitmap
is a matrix of squares called pixels
(pixel = picture element) which
all have their own color.
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The human eye is not capable of seeing each individual pixel so we perceive a picture with smooth gradations.
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The number of pixels you need to get a realistic looking image depends on the way the image will be used.
That is, the resolution
at which it will be viewed.
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Printed material like a magazine or photo needs a resolution of
2400 dots (pixels) per inch, while a computer screen is more like
72 or 96 pixels per inch.
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Bitmap images...
- Appropriate for continuous-tone images
- Photographs
- Artwork created in "paint" programs
or scanned-in
- Disadvantages:
- Contain a fixed number of pixels
- Can loose detail and appear jagged or
grainy when scaled up on screen or
printed at a lower resolution than
which they were created
File formats that are used for bitmap data
Bitmap data can be saved in a wide variety of file formats. Among these are:
- BMP: is a standard file format for computers running the Windows operating system. The format was developed by Microsoft for storing bitmap files in a device-independent bitmap (DIB) format that will allow Windows to display the bitmap on any type of display device. The term "device independent" means that the bitmap specifies pixel color in a form independent of the method used by a display to represent color.
This is the format used in Windows "screen shots". (Print_Screen or
Alt+Print_Screen)
- EPS: flexible file format that can contain both bitmap and vector data. Encapsulated PostScript (EPS) is a standard file format for importing and exporting PostScript files.
- GIF: mainly used for internet graphics Although GIF does not require a specific resolution, most GIF images have a resolution between 72 and 90 dpi, ideal for on-screen display.
GIF is the abbreviation of Graphics Interchange Format.
It was originally developed by CompuServe (an on-line service that was pretty successful in the early nineties). The format includes some key features which makes it a unique and valuable format for the internet. These features include file compression, transparency, interlacing and storage of multiple images within a single file which allows for a primitive form of animation.
- JPEG stands for Joint Photographic Experts Group, which is a standardization
committee. It also stands for the compression algorithm that was invented by
this committee.
To complicate things a bit more, JPEG compressed images are
often stored in a file format called JFIF (JPEG File Interchange Format), which
a lot of people also refer to as JPEG!
- PICT is a file format that was developed by Apple Computer in 1984 as the native format for Macintosh graphics. PICT files are encoded in QuickDraw commands. The PICT format is a meta-format that can be used for both bitmap images and vector images.
PICT files are primarily used to exchange graphics between various Macintosh applications. It is generally a better idea to use the TIFF or EPS file format instead of PICT.
For MacOS X, Apple has decided to replace PICT by PDF.
- PDF stands for Portable Document Format. As the name implies, it is a data format that can be used to describe documents.
Adobe, the developers of PDF and also the inventors of PostScript, market software to create, edit and visualize PDF files.
Because the specifications of the file format are publicly available, a lot of other companies develop software for PDF as well.
Using PDF is as close to having a paperless office as we can currently get!
- TIFF or the Tagged Image File Format is a rather old standard that is still very popular today. It is a highly flexible and platform-independent format which is supported by numerous image processing applications.
TIFF is strictly used for bitmap data. It doesn't contain text nor vector data.
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Vector graphics are images that are completely described using mathematical definitions.
The figure below shows the principle. To the left you see the image itself and to the right you see the actual lines that make up the drawing. |
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Each individual curve is made up of either a vast
collection of points with line segments interconnecting all of them or just a few control points that are connected using so called
bezier curves. It is this latter method that generates the best results and that we will be working with in
Adobe PhotoShop.
The figures below demonstrate the two principles. To the left a bean shape is formed by connecting a number of points using straight lines. To the right, you see the same bean shape that is now drawn using only 4 points
(anchors).
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The file formats that use vector format data are:
EPS, PDF, and
PICT. |
Getting started:
Before you start this assignment, be sure that you have completed the first two Photoshop assignments. (Recall the flowers and tomatoes?!)
Start Photoshop and open a new window. Create a 3 x 3 inch document that has a resolution of 300 pixels/inch. The Color Mode is RGB Color 8 bit.
Make sure that the Background Contents is White.
The name of this document should be: paths-1-cg3faa
(Note: the cg3faa should be subsituted for your account number!)
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Paths and Pens
The Pen tool draws paths with the greatest precision.
The Magnetic Pen tool and the Freeform Pen tool draw paths as if you were drawing with a pencil on paper. |
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On the tool options bar, select or verify the following settings:
1. Select the Paths option.
2. Click the arrow for Geometry Options and make sure that the Rubber Band check box is not selected in the Pen Options pop-up palette.
3. Make sure that the Auto Add/Delete option is selected.
4. Select the Add to Path option. |
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Click the Paths tab to bring that palette to the front of the Layers palette group.
The paths palette displays thumbnail previews of the paths you draw.
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| Currently, the palette is empty because you haven't started drawing. |
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As you go through the assignment, pay attention to little details that can provide information about the tools that you are working with. |
Making your groovy flower using paths.
Click here to get the petal template. (It should look like the figure on the right.)
Save the file in your folder and then open it with Photoshop CS2.
Note: in the Save dialog,
click the desktop icon to the left, then use the
"Class Resources" you find there to drill down your
hw2 folder. |
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Please, read over the instructions before you begin.
Only do each step exactly as described. Random clicking when working with paths can lead to frustration very quickly.
Pay particular attention to the difference between an Anchor point (they are square) and direction lines (they are a line segment with small circles at the ends).
When working with the template file, the blue squares, represent anchor points and the red circles represent the endpoint of a direction line.
At the end of this step, you will have the first anchor point (A) and the direction of the first curve. |
Step 1.
Be sure to release the left mouse button after dragging it to red-dot 1.
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When you click on B, the segment is curved because of the direction line that you set in step 1.
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Step 2.
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Step 3.
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Step 4.
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Step 5.
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At any point in this excercise, you can manipulate the path or the points by using the Path Selection Tool/Direct Selection Tool.
For instance, if your figure looks like...
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Should your figure look something like this, use the
Direct Selection Tool and click near A or C, and then
drag until you get something more like the figure in
step 5. above
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One can not only manipulate anchor points using the Direct Selection Tool, but also modify the direction and the length of the direction lines.
When you use the Path Selection Tool, you can modify the path.
It is productive to practice using both the path tool and then working with the two types of selection tools to gain an intuitive understanding of how all of these tools work together. |
When you are working with the Path/Direct Selection Tools there are a variety of options when you click the right mouse button. You can delete the anchor point, delete the path or make a selection.
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The Make Selection option works just like the Magic Wand and the Marquee Tools. |
Save and duplicate your path!!!!
As you draw paths, a temporary storage area named Work Path appears in the Paths palette.
Once you have made your first petal, (the three points with direction lines in the exercise above) save that path as:
petal-1.
Double click the Work Path and you will get a pop-up menu.
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Right click petal-1 and a pop-up menu appears.
Duplicate path.
Then save it as petal-2.
Repeat these steps until you have 7 (seven) petals in all. |
You now have 7 identical Work Paths named petal-1 through petal-7.
The paths palette should look like the figure on the right.
This is a good time to save your work. |
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Convert the paths into a selection.
Step 1. Select the Layers palette.
Step 2. Make a new layer.
Step 3. Hide the petal template layer.
What you see is the path of the petal that you did in the previous step.
Go back to the Paths palette and select
petal-1.
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You must convert a path to a selection in order to fill it, stroke it, or apply a filter.
Step 1. In the Paths palette, click petal-1 path to make it active.
Step 2. Convert the petal-1 path to a selection by doing one of the following:
- From the Paths palette menu (right click petal-1), choose Make Selection, and then click OK to close the dialog box.
- Drag the petal-1 path to the Load Path as a Selection button of the Paths palette.
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Go to the Layers palette. Make sure that you are on a new layer.
Fill the selection. Edit>Fill
There will be a pop-up menu that you will need to fill out with your fill choices.
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| Fill the petal selection. |
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To work with the same selection again to make another petal in the flower...
select the marquee tool and make sure that you are working on a new layer. |
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Move and transform the selection that you have.
Select>Transform Selection>Rotate
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Repeat
(Click Marque Tool; make new layer; Select>Transform, then
rotate; move petal to new position; select a new color;
Edit>Fill) until you have made a flower with six petals. Have each petal on a different layer with a different color.
Your flower should look somewhat like this:
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The point of this exercise is to give you practice making paths, and then transforming the paths.
The paths can then be converted into selections and selections can be converted into paths as the next section will go over.
Remember, in Photoshop, you can achieve the same effect a number of different ways. The power of vector graphics is that it maintains its crispness as it is scaled. If you were working for a company, and you had this flower as your logo, then you could make large images for T-shirts or small images for stamps! |
Making multiple selections over many layers.
Using the Magic Wand tool, select a petal. Make sure that you are in the layer you last created.
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To add to the previous selection, follow the three steps outlined in the figure.
Step 1: make sure that you are on the appropriate layer. In this case you are supposed to be on the green petal layer.
Step 2: have the magic wand selected.
Step 3. While holding down the shift key, click on the green petal to add to your current selection.
Repeat these steps until you have the entire flower selected. |
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Make a Work Path from selection.
You can get this menu by right clicking and this pop-up menu will come up.
Select Make Work Path. This pop-up menu will appear. 2.0 pixels is ok.
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Go to the Paths palette and then save the Work Path as flower-1.
Use this new path to make multiple copies of the flower - you can fill it with different colors and apply a filter much like you did for tomato assignment.
- New layer
- Paths palette, select flower-1, then right click, and Make selection
- Select>Transform
- Fill
- Apply a Filter
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Your final product should look something fun like this:
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Save your file in two formats:
Save your file as a JPEG format into your
hw2 folder on the class server
- File>Save As
- select JPEG as the file Format option
- use flower-power-cg3f__ as the file name (where the blanks represent your account number.)
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Likewise, save your file in Photoshop (PSD) format into your
hw2 folder.
- File>Save As
- select Photoshop (PSD) as the file Format option
- use flower-power-cg3f__ as the file name (where the blanks represent your account number.)
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| If your account were cg3fyy, you should have the following two files saved on your file server: |
flower-power-cg3fyy.jpg
flower-power-cg3fyy.psd
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Portions ©opyright 2006 Mary ET Boyle
Last updated:Sunday, October 1, 2006
Modified October 2007, mrw
