Graphics - Photoshop Tutorial, Guides for Photoshop. Deenbandhu Chhotu Ram University of Science and Technology
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Graphics - Photoshop Tutorial, Guides for Photoshop. Deenbandhu Chhotu Ram University of Science and Technology

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Photoshop tutorial to teach things in best way. These slides talks about: Graphics, Bitmap, Vector Graphics, Types of Graphics, Photographic Images, Graphic Format for the Web, Format for Print, Standard Photoshop File, ...
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Graphics Overview: Using Photoshop

Computer graphics boil down to two basic types: (bitmaps and vectors )

1. Bitmap (or raster) graphics: • Bitmap graphics are stored as a series of tiny dots called pixels. • Each pixel is assigned a color, and when they are viewed all together, they form

the picture. • Bitmap graphics can be edited by erasing or changing the color of individual pixels. • There are many different bitmap file formats:

• TIFF for print; Photoshop's PSD and BMP; and • GIF, JPG, and PNG for the Web.

2. Vector graphics: • Unlike bitmaps, vector graphics are not based on pixel patterns, but instead use

mathematical formulas consisting of lines and curves that make shapes. • Vector graphics are ideal for illustrations, line art, and type. • However, with the exception of Macromedia's Flash and Shockwave formats, most

browsers do not support vector graphics. • As a result, vectors have to be converted to bitmap (rasterized) before being

displayed on the Web. • Some vector graphics file formats include: EPS; Illustrators' AI and WMF; and PICT

for the Mac.

Types of graphics

1. Photographic images: • Continuous tones, 24 bit color, no text, few lines and edges

2. Graphics, Logos, Line art and Screen Captures: • Solid colors, up to 256 colors, with text or lines and sharp

edges

Image mode (RGB, indexed color, Gray scale, CMYK)

• RGB:

• Uses millions of colors. Flexible for editing.

• Use when working on editing or creating an image (millions of colors).

• Save file as .psd . Remember when saving in PSD, this will produce a large file and will not be viewed on the web. The PSD file is good to use while editing file.

• Layers are available in this mode and not in gif or jpg, or png (they are compressed/ flattened files)

• Jpg/png24, uses RGB but NOT gif.

• CMYK:

• The CMYK model is based on the light-absorbing quality of ink printed on paper.

- Pure cyan (C), magenta (M), and yellow (Y) pigments should combine to

absorb all light and produce black. For this reason these colors are called subtractive

colors.

- Use when working on images for print and save as .tiff and use high resolution (200-600).

- Indexed color mode:

• 8bit or 256 colors. Used with .gif files. Not flexible to use while editing and you will get chunky result

Resolution

• Resolution

• 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).

• Resolution for the screen/web (dependant on monitor size):

• 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.

• Use 72 - 200 resolution for web (Note: if use higher resolution than 72, your file size will increase and dimensions of height and width as well)

• Resolution for printer: • 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

• Use 200- 1200 resolution for printing

Working with mode:

To change your image over to RGB mode:

- select Mode from the Image pull down menu and choose RGB Color.

To resize image:

go back to the Image pulldown and select Image Size. Enter in the size you want (either the pixel dimension or in inches - make sure the resolution box reads "72") and click OK.

Graphic format for the web/screen: GIF: Graphic Interchange Format • First graphic format for the web created by CompuServ • Standard gif is 8bits or 216 colors • Transparent gif: GIF89a (No background color: blends into any

background since it doesn’t have any background color of is own)

• Gif uses “LZW” (Lemple-Zev-Welch) compression. • This compression takes advantage of the repetitions in

data streams. • LZW is efficient for storing simple graphic, flat colors,

Banners, logo’s (images with little color shading)..

Graphic format for the web:

• Jpeg or JPG: Joint Photographic Experts

• 24 bits... Millions of colors

• used for photograph and complex images

• Uses Lossy compression method: • which compresses shades of tones that are not visible by the eye without

loss of quality

• Used to compress photographs

PNG (png8 and png 24):

 PNG: Portal Network Format

 Types of PNG:

Png_8: 8 bits.. 256 colors, good for simple graphics .. Not too many shades of colors

Png_24: 24 bits or millions of colors. Good for complicated images such as photographs.

 Lossless compression scheme and better compression than gif

Format for Print/editing/scan: Tiff : (great quality image used for print)

• TIFF - Image File Format (.TIF files).

• TIF files are large, huge even, but it's the price we pay, it's how large

the data is.

• TIFF is the most universal format, about any program on any

platform will handle TIFF.

• TIFF has been the format of choice for use for master copies of

scanned data for years.

• TIFF was developed by Aldus, before Adobe bought them, and is the

most widely supported format across other platforms.

• Not used on the web

• Great for print (good quality), but remember that it’s a large file

PSD: standard Photoshop file(.psd)

• Uses millions of colors (RGB: red, Green, & blue)

• (0-256 shades of red, 0-256 shades of Green, 0-256 shades of blue)

• Great for editing / work in progress

• Saves with layers / helpful while editing a file

• Very Large file

• PSD file format will not work on the web … (except in Safari under

Mac OS X... Which will display a flattened version of your image.)

Other formats: These formats are not commonly used on the web (as they are not supported by all browsers)

• BMP (Windows Bitmap)

• BMP will handle 24 bit data but it cannot be compressed.

• BMP uses RLE (Run Length Encoding) to compress 8 bit data, which is

effective in graphics, but much less effective in continuous tones like

photos.

• PICT (Macintosh Quickdraw) PICT is used in page layout and graphics

programs; it creates large files and is not suitable for exchange with Windows

programs.

Browser color palette:

 Browser Safe palate ( web):

 Browser uses 256 colors (8 bits).

 40 colors are reserved for its own use

 216 colors are used by the browser

 Dithering: browser tries to substitute colors if not part of its palate

 Interlace: browser will display image gradually

 Anti-alias: blending of pixel colors on perimeter of hard-edge shapes. Smooth edges and not jagged

• Photoshop tips for the web

Graphic format for the web/screen:

• File formats to use: gif, jpg or png

• To save for the web using Photoshop: • From the FILE menu, select SAVE FOR WEB and then select the desired web

format from the window that comes up.

• Make sure you select “0” dithering colors (minimal loss of color)

General Photoshop tips (such as after scanning)

• To reduce image size and resolution: • From the image menu, select “image size” • You can also use the “Crop” tool to remove parts of the image along the

perimeter

• You can change the orientation of the image: • From the image menu, select “Rotate canvas”

• To restore some lost information after resizing image (or scanning) • Apply “unsharp mask”: from “filter menu” choose sharpen then select “unsharp mask” • You can also try to adjust colors (after scanning or changing size of image): • Image menu: select adjustments, then try the following • Curves

• Auto levels

• Auto contrast

• Variations

Useful Chart when working with image (web vs print)

Image type Editing image/While working on with image

Output to screen/web Output to printer

Photograph

(complicated image)

Mode: RGB: best for web

Save file as: .psd

CMYK: mode used for printing

Save file as: .tiff

Format: Jpg or png

Mode: RGB

-Millions of colors

Resolution: 72-200

The lower resolution, the lower file size

Format: .tiff or .pict

- mode: CMYK

-Millions of colors

-resolution200-600

Line art image

(simple image)

Mode:

RGB: mode best for screen

Save file as: .psd)

CMYK:mode used for printing

Save file as: .tiff

Format:

Gif or png8

-256 colors (mode: index)

Resolution:72

The lower resolution, lower file size

Format:

.tiff or pict

-Millions of colors

-resolution: 200-600

Mode: CMYK

Scanning Scan at high resolution

150-300 web

200-600 print

After scanning and editing image, save for desired output as mentioned above

Move object tool

- Rectangular marquee tool - press to select Elliptical Marquee tool

- Crop tool

- used to Shrink image. You can also use to enlarge image

- Paint bucket tool

- used to paint large area of canvas. It uses colors in the foreground

-Type tool

- Eye dropper tool

-to select a foreground color from image

-Foreground color

- used when using type, paint bucket, pecil, paint brush

-Background color

- used when “cut” from edit menu

-Pencil tool: free hand drawing (uses foreground color)

- Press on same tool to select a “Brush” tool

Overview of Photoshop tools

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