Photoshop Basics

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Contents Introduction .................................................................................................................................................. 2

Color Mode (RGB and CMYK) ........................................................................................................................ 2

RGB Color Mode .................................................................................................................................... 2

CMYK Color Mode ................................................................................................................................. 2

Resolution and DPI ........................................................................................................................................ 3

Graphic File Format ....................................................................................................................................... 3

PhotoShop Interface ..................................................................................................................................... 4

The Menu Bar ........................................................................................................................................ 5

Options Bar Or Tool Bar ........................................................................................................................ 5

Tool box ................................................................................................................................................. 5

Layers .................................................................................................................................................... 8

Resolution / Dimensions of Image / Size of File ........................................................................................... 9

Image Size Dialog Box ........................................................................................................................... 9

Levels........................................................................................................................................................... 11

Note: Download Notes from MasterShadab.blogspot.com

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Introduction

Color Mode (RGB and CMYK)

The color systems used by scientists and artists are entirely different. An artist will mix blue and

yellow paint to get a shade of green; a scientist will mix green and red light to create yellow. The

printed page in a magazine is yet another system.

It's important to define the two different kinds of color that we see in the world as the first step in

understanding color systems. First, there's the color you can touch, such as the skin of an apple

or a painted wall. These colors are part of the surface of an object. Next, there's the color you

can't touch, such as a beam of red light and the colors produced by your computer monitor.

RGB Color Mode RGB is the color scheme that is associated with electronic displays, such as CRT, LCD monitors,

digital cameras and scanners. It is an additive type of color mode, that combines the primary

colors, red, green and blue, in various degrees to create a variety of different colors. When all

three of the colors are combined and displayed to their full extent, the result is a pure white.

When all three colors are combined to the lowest degree, or value, the result is black.

Additive Color System

Red - Green - Blue (RGB)

CMYK Color Mode Printers print color onto paper using the CMYK color mode only. This is a four color mode that

utilizes the colors cyan, magenta, yellow and black in various amounts to create all of the

necessary colors when printing images. It is a subtractive process, which means that each

additional unique color means more light is removed, or absorbed, to create colors. When the

first three colors are added together, the result is not pure black, but rather a very dark brown.

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The CMYK Color System

Cyan - Magenta - Yellow - Black

Resolution and DPI The Resolution of an image describes how fine the dots are that make up that image.The more

dots, the higher the resolution (better quality). When displayed on a monitor, the dots are called

pixels.

A 640-by-480-pixels on screen is capable of displaying 640 distinct dots on each of its 480 lines,

or about (640 X 480) 300,000 pixels.

DPI means dots per inch and it is used in printing, A 300 dpi (dots per inch) printer is capable of

printing 300 dots in a line “1 inch” long. This means it can print 90,000 (300 X 300) dots per

square inch.

Graphic File Format There are a number of different types of graphics file formats. Each type stores graphics data in a

different way. The most common image file formats, the most important for cameras, printing,

scanning, and internet use, are JPG, TIF, PNG, and GIF.

JPG (Joint Photographic Experts Group)

Digital cameras and web pages normally use JPG files - because JPG heroically compresses the

data to be very much smaller in the file. A JPEG is compressed in a way that loses some of the

image detail during the compression in order to make the file small (and thus called “lossy”

compression).

TIFF (Tagged Image File Format)

TIFF images create very large file sizes. TIFF images are uncompressed and thus contain a lot of

detailed image data (which is why the files are so big) TIFFs are also extremely flexible in terms

of color

GIF (Graphic Interchange Format)

This format compresses images but, as different from JPEG, the compression is lossless (no

detail is lost in the compression, but the file can’t be made as small as a JPEG).

GIFs also have an extremely limited color range suitable for the web but not for printing. This

format is never used for photography, because of the limited number of colors.

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PNG ( Portable Network Graphics)

It was created as an open format to replace GIF, because the patent for GIF was owned by one

company and nobody else wanted to pay licensing fees. It also allows for a full range of color

and better compression.

PSD (Photoshop Document)

It is the default format that Photoshop uses for saving data. PSD or PDD is a widely accepted file

format. PSD supports all available image modes. The PSD format is extremely useful as it can

support duotones, clipping paths and channels.

PhotoShop Interface

Photoshop is unlike other common software interfaces which emulate virtual typewriters or

graphing paper. Photoshop creates an artist's virtual studio/darkroom. When you open the

program you see a toolbox on the left with tools you will use to manipulate your images, and on

the right, a white square which is your "canvas" or work area. The gray area surrounding the

canvas is not part of your image, but only defines its edges.

To change the canvas dimensions, go to Image > Canvas size. You can type in any dimensions you like,

but remember that the area of the image is directly proportional to the file size.

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The Menu Bar

At the very top of the screen as always is the Menu Bar, a common feature of most programs

these days. Clicking on the various menu headings brings up a list of related options and

commands. For example, the File menu is where we find options for opening, saving and closing

Photoshop documents. The Layer menu contains options for working with layers. Photoshop’s

many filters can be found under the Filter menu, and so on:

Options Bar Or Tool Bar

The Options bar appears at the top of the screen and is context sensitive, changing as you change

tools. The tool in use is shown in the left corner, and options relating to the tool appear to the

right of that.

If you select the Crop Tool from the Tools panel, the Options Bar changes to display options for

the Crop Tool:

If you select the Move Tool from the Tools panel, the Options Bar changes to display options for

the Move Tool.

And if you select the Type Tool, we see options displayed for the Type Tool:

Tool box

Along the left side of the screen is Photoshop’s Tools panel, formerly known as the Tools

palette (palettes are now officially known as panels in Photoshop CS4), and also commonly

referred to simply as the Toolbox. This is where we find all of the various tools we need for

working on our images.

Some Basic tools in photoshope are as follows:

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Marquee Tool: The images in Photoshop are stored pixel by pixel, with a code indicating

the color of each. The image is just a big mosaic of dots. Therefore, before you can do anything

in Photoshop, you first need to indicate which pixels you want to change. The selection tool is

one way of doing this. Click on this tool to select it, then click and drag on your image to make a

dotted selection box. Hold shift while you drag if you want a perfect square or circle. Any pixels

within the box will be affected when you make your next move. If you click and hold on this tool

with your mouse button down, you will see that there is also an oval selection shape, and a crop

tool .

ToolBox

Crop Tool: . To crop your image, draw a box with the crop tool. Adjust the selection with

the selection points, and then hit return to crop.

Lasso Tool : The lasso tool lets you select freeform shapes, rather than just rectangles and

ovals.

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Magic Wand: Yet another way to select pixels is with the magic wand. When you click on

an area of the image with this tool, all pixels that are the same color as the pixel you clicked will

be selected. Double click on the tool to set the level of tolerance you would like (i.e. how similar

in color the pixels must be to your original pixel color. A higher tolerance means a broader color

range).

The Move Tool: This is a very important tool, because up until now all you have been able

to do is select pixels, and not actually move them. The move tool not only allows you to move

areas you have selected, but also to move entire layers without first making a selection. If you

hold the option (or alt) key while clicking and dragging with the move tool, you can copy the

selection.

Airbrush Paintbrush and Pencil tools can be used to draw with the

foreground color on whichever layer is selected. To change the foreground color, double-click on

it in the toolbox. You will then see a palette of colors from which to choose. Select one and click

OK. To change the brush size, go to Window > Show Brushes.

Eraser Tool: Erases anything on the selected layer. You can change the eraser size by

going to Window > Show Brushes.

Line Tool: Can be used to draw straight lines. Click on the tool to select it, then click with

the tool on the canvas area and drag to draw a line. When you release the mouse button, the line

will end. You can change the thickness of the line or add arrowheads to it by double clicking on

the tool to see this dialog box:

Text tool: Click on this tool to select it, then click in the Canvas area. You will be given a

dialog box in which to type your text, and choose its attributes. Each new block of text goes on

its own layer, so you can move it around with the Move Tool. Once you have placed the text,

however, it is no longer editable. To correct mistakes, you must delete the old version (by

deleting its layer) and replace it.

Eyedropper: Click with this tool on any color in the canvas to make that color the

foreground color. (You can then paint or type with it).

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Magnifier: Click with this tool on a part of your image you want to see closer, or drag with

it to define the area you want to expand to the size of the window. Hold down

the Option or Alt key to make it a "reducer" instead and zoom back out.

Grabber: Click with this and drag to move the entire page for better viewing.

Layers

Photoshop works on a system of layers, which are like sheets of transparency. When you place

objects on a layer, they become part of the layer, just as if you had drawn on a transparency with

a marker. If two objects are on the same layer and you want to move them closer to each other,

you need to cut them out with the lasso or marquee tool and physically move them together. If

they are on different transparent layers, however, all you have to do is move the layers with the

move tool until the objects are closer to each other.

In a file with overlapping

elements, putting them on

different layers allows me to

move them around without

having to select them first.

To see all the layers in your

document, go to Window >

Show Layers. Here are the layers

for the image on the left. The eye

icon on the left indicates that the

layer is visible. Click on the eye

to make a layer invisible. Select a

layer and then click the trash icon

at the bottom to delete a layer.

Click and drag on layers to

change their stacking order.

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Resolution / Dimensions of Image / Size of File

Pixels per Inch

Photoshop files are made up of tiny squares of color called pixels. Using large pixels will make a

grainy image, and using tiny pixels to make the same image will be much smoother. However,

the smaller the pixels, the more of them there are in the file, and the larger the file size will be. If

the file size is large, it opens slower, takes longer to save, and takes up more room on a disk. The

the key in choosing a resolution is finding the balance between image quality and file size.

For example, if I want to re-tile my bathroom floor to make a smiley face, I can either use large

tiles or small tiles. On the left I use 10 tiles on each side for a total of 100 tiles. On the right I use

25 tiles on each side, for a total of 625 tiles.

.

If each of these images measures an inch on each side and each tile is a pixel, the image on the

left would have a resolution of 10 pixels per inch, or 10 ppi. The image on the right would be 25

ppi. Notice how a small increase in resolution corresponds to a much larger increase in file size,

because the increase is exponential.

You can begin to see why images of different resolutions sometimes change size when combined

in one file, or when brought into other programs. For instance, what if I wanted to draw the

image on the right in tiles the size of the image on the left? I would have a much larger image in

the end. This is what happens when you bring an image with a high resolution into a file which

has a lower resolution. There can only be one resolution per file, so the pixels of the image

coming in are resized to the size of the existing pixels in the file.

Image Size Dialog Box

JPEG images from the Internet have a low resolution of 72 dpi. However there is no reason that

your JPEG images have to have such a low resolution. Image files generated by digital cameras

often begin with a low resolution but very large dimensions. You can use that to your advantage

by trading area for resolution. To change the resolution or the size of your image, go to File >

Image Size. It will look something like this.

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At the bottom of the window there is a box marked "Resample Image". This box determines

whether or not area can be exchanged for resolution. When it is checked, resolution remains

independent of the image dimensions. If you change the dimensions or the resolution, you will

see the file size change accordingly.

To exchange area for resolution, uncheck the Resample Image box:

You can see that the linking symbol on the right now encompasses width, height and resolution.

Perhaps you don't need a 10 inch wide image. If you make the width smaller, look what happens

to the resolution:

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What is happening is simply that the pixels in your image have been decreased in size. The total

number of pixels and therefore the file size remains the same. If you had used the resample

option, pixels would have been added or removed from the image and the file size would have

increased or decreased.

What resolution is best?: 300 is optimal, between 200 and 300 is okay, but below 200 the

image will begin to show pixelation.

Levels

Sometimes an image will seem faded or washed-out. Using the Levels adjustment can increase

the contrast in the image. Go to Image > Adjust > Levels. You will see this dialog box with a

histogram showing the tonal values in the image. Here the curve is shifted to the right, which

corresponds to what we can see--the image is too light.

By moving the circled sliders toward the bell-shaped part of the curve, we can reset the value of

the darkest and lightest pixels in the image. Moving the black arrow to the right will darken the

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darkest values in the image, and moving the white slider to the left will lighten the lightest values

in the image.

Watching how the changes affect the image, let's gradually move the sliders inward to the edges

of the curve.

When we click OK, Photoshop will reset the curve, with our placed arrows as endpoints:

(Going back into Levels, we can see our new tonal values curve)

As you can see, what the levels adjustment did was take a segment of the tonal range and

reassign the values from black to white. In the readjusted levels dialog box, you can see spaces

indicating values that no longer exist. This is the difficulty in making image adjustments. When

you over-adjust, you begin to leave gaps in the tonal range, and this will eventually cause a

posterized look (too much black & white and not enough middle gray tones). The only way to

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avoid this is to capture a large range of tonal values when scanning or taking a picture, and to use

only subtle adjustments to the images.

Using Levels on color images:

In this image the background wasn't quite black. Moving the dark slider to the right deepened the

darks.

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Values are lacking at both ends

of the curve. Move sliders inward

Click with highlight dropper in

the lightest part of the image to

correct color imbalance.