INTRODUCTION TO COMPUTER GRAPHICS

Transcription

1 INTRODUCTION TO COMPUTER GRAPHICS ITC 31012: GRAPHICAL DESIGN APPLICATIONS AJM HASMY

2 WHAT CAN PS DO? - PHOTOSHOPPING CREATING IMAGE Custom icons, buttons, lines, balls or text art web design ALTERING IMAGE Altering an image includes doing such things as changing the colors within an image, modifying the size and scale of an image, or putting one picture "within" another. Alteration also includes technical modifications such as changing the mode of image compression from one type to another, or changing the number of bits used per pixel

3 PHOTOSHOPPING..

4 WHO USES PHOTOSHOP PHOTOGRAPHERS PUBLISHERS SCIENTIFIC RESEARCHERS TECH COMMUNICATORS

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7 Photoshop CS6 system requirements (Windows) Intel Pentium 4 or AMD Athlon 64 processor Microsoft Windows XP with Service Pack 3 or Microsoft Windows 7 with Service Pack 1. Adobe Creative Suite 5.5 and CS6 applications also support Windows 8 and Windows 8.1. See the CS6 FAQ for more information about Windows 8 support.* 1 GB of RAM 1 GB of available hard-disk space for installation; additional free space required during installation (cannot install on removable flash storage devices) 1024 x 768 display (1280 x 800 recommended) with 16-bit color and 512 MB (1 GB recommended) of VRAM OpenGL 2.0 capable system DVD-ROM drive This software doesn't operate without activation. Broadband Internet connection and registration are required for software activation, validation of subscriptions, and access to online services.

8 ALTERNATIVES

9 CHARACTERISTIC OF COMPUTER GRAPHICS PIXEL COLOR MODES RASTER & VECTOR IMAGES IMAGE TYPES NOISE

10 Improving image quality by Eliminating noise Enhancing contrast Eg: A "noisy" image Smoothed Continued

11 PIXEL A picture can describe as a set of intensities of the pixels WHAT IS A PIXEL? The smallest addressable unit on a display screen All pictures are made of pixels. And it is the smallest element of an image. Zoom

12 RASTER VS VECTOR IMAGE If an image stores its picture information as intensities of individual pixels it is referred as a Raster Image If an image stores its picture information as geometric structures it is referred to as Vector Image

13 VECTOR GRAPHICS Stores image information using points and curves. Contains instructions for drawing lines, circles, ellipses, curves, and other shapes. Uses mathematical formula Vector graphics can be edited and manipulated far easier than raster images. Easy to work with individual shapes separately Consumes less disk space Not suitable for images contains natural scenes Vector graphics can be scaled up and down easily and quickly while retaining the quality of the picture Example for vector graphics base designing tool- corel draw

14 RASTER GRAPHICS Uses pixel values to describe an image. File size is independent of the image complexity. For higher resolution, file size increases. Suitable for natural images Image loose its quality when scaling and zooming Example for raster graphics based image editing tool Adobe Photoshop

15 Zoom Raster Vector

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17 RASTERIZING GENERATING PIXEL BASED INFORMATION FROM VECTOR IMAGES HARD TO CONVERT RASTER IMAGE TO A VECTOR IMAGE

18 If I am creating a new design which software should I use; Raster or Vector Graphic Program? It depends on the design itself. If it's going to have photographic elements with continuous tones and blends of color, you are probably better off using a paint program like Photoshop which is a raster program that specializes in photo editing, or use any other PAINT program. If you want your final design to look like an illustration instead with clear contrasts between objects & shapes, then use a vector program. You MUST use a vector program when creating art for plotters, vinyl-cut signs, engraving and other specialty items. Ideally a company that has a logo design with photographic elements, also has a secondary version of their logo in vector format that can be used for those specialty items that require vector art.

19 DPI VS PPI DPI - DOTS PER INCH This is the amount of ink dots the printer will put on each pixel of your image. The DPI is set by the actual printer device. PPI - PIXELS PER INCH Digital raster images are measured in pixels, or picture elements. How many pixels per inch is determined by the device you create the digital image with: camera, scanner, or graphics software and can be modified with a photo editing software like photoshop.

20 IMAGE COMPRESSION WHY COMPRESSION? To store images using less disk space To reduce the transferring time( network) To reduce loading time DISADVANTAGES Loose quality

21 TYPES OF COMPRESSION LOSSLESS COMPRESSION - All image detail and color information is retained as the image is compressed. This retains image sharpness and clarity as in the source LOSSY COMPRESSION - Image color or image detail information is reduced to compress the image. Lossy compression makes much smaller image files than lossless. Always use lossless compression while editing images. Only the final image should be compressed in a lossy format, and only if small file size is of primary concern (like internet web images, for example).

22 HOW COLOUR INFORMATION STORED Each pixel is assigned with set of bits Number of bits used to store color information of a pixel is called bit-depth Bit depth can be varies from 8 to 24 Higher bit depths will increase the quality as well as file size What is the size of a image file which use 24 bits to store colour information and resolution is 1024x768? (this file format uses compressions algorithm which has the compression ratio 8:1)

23 IMAGE FILE FORMATS DIFFERENT FILE FORMATS USE DIFFERENT TECHNIQUES TO STORE IMAGE INFORMATION BMP: Bitmap file format is used for bitmap graphics on the windows platform. Unlike other file formats, which store image data from top to bottom and pixels in red/green/blue order, the BMP format stores image data from bottom to top and pixels in blue/green/red order. Compression of BMP files is not supported, so they are usually very large. These files contains ".Bmp " extension.

24 IMAGE FILE FORMATS GIF: GRAPHICS INTERCHANGE FORMAT This was originally developed by compuserve in Most popular file formats for web graphics The gif format supports 8 bits of color information or less. In addition, the gif89a file format supports transparency, ( compuserve gif(87) does not support transparency.) This feature makes gif a particularly popular format for web images. This uses a "lossy" compression method. It reduces an image's file size by removing bits of color information during the conversion process. This file format also support animations. Uses ".Gif" as extension.

25 IMAGE FILE FORMATS JPEG: JOINT PHOTOGRAPHIC EXPERTS GROUP FORMAT This is the most popular formats for web graphics. It supports 24 bits of color information, And is most commonly used for photographs and similar continuous-tone bitmap images. This is a compressed file format and uses lossy compression strategy. This use to save only the color information that is essential to the image. Jpeg does not support transparency. The jpeg file format supports millions of colors. In theory, JPEG was designed so that changes made to the original image during conversion to JPEG would not be visible to the human eye. These files contains ".Jpg" as extension

26 IMAGE FILE FORMATS PNG: THE PORTABLE NETWORK GRAPHICS FORMAT This consider as the successor to the GIF file format. It is platform independent and should be used for single images only (not animation). Compared with gif, png offers greater color support and better compression, gamma correction for brightness control across platforms, better support for transparency, and a better method for displaying progressive images. Png format uses ".Png" as extension

27 IMAGE FILE FORMATS TIFF: TAG INTERCHANGE FILE FORMAT This is a tag-based format that was developed and maintained by aldus (now adobe). This is compatible with a wide range of software applications and can be used across platforms such as Macintosh, Windows, and Unix. The tiff format is complex, so tiff files are generally larger than gif or jpeg files. Tiff supports lossless lzw (lempel-ziv welch) compression; however, compressed tiffs take longer to open. Extension used is ".Tif"

28 ??? HOW TO SAVE A PICTURE FILE IN DIFFERENT FORMATS?