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Introduction to Computer Graphics program 2025
- 1. COMPUTER GRAPHICS UNIT-1 Pixels AndAspect Ratio 1 By Prof. Phadtare Tushar JSPM’s Bhivarabai Sawant Institute of Technology & Research, Wagholi, Pune Department of Computer Engineering
- 2. JSPM’s Bhivarabai Sawant Instituteof Technology and Research, Wagholi,Pune-412207 Department of Computer Engineering • Departmental Vision Empowering the students to be professionally competent & socially responsible for techno-economic development of society. • Departmental Mission To provide quality education enabling students for higher studies, research and entrepreneurship To inculcate professionalism and ethical values through day to day practices. 2
- 3. • Institute Vision "Satisfythe aspirations of youth force, who want to lead nation towards prosperity through techno-economic development." • Institute Mission To provide, nurture and maintain an environment of high academics excellence, research and entrepreneurship for all aspiring students, which will prepare them to face global challenges maintaining high ethical and moral standards." 3 JSPM’s Bhivarabai Sawant Institute of Technology and Research, Wagholi,Pune-412207 Department of Computer Engineering
- 4. CO’s 1) To explorethe principles of Object Oriented Programming (OOP). 4 1 To understand structure & operation of various hardware devices and to recognize file formats & graphics libraries used in computer graphics 2 To understand and analyze different scan conversion algorithms 3 To implement polygon filling, windowing and clipping algorithms and compare their performance 4 To interpret, use 2D and 3D geometric transformations. 5 To apply techniques of hidden surfaces, light effects, shading, curve generation and fractals in construction of natural objects. 6 To experiment advanced animations and gaming techniques to create animation by using modern graphics tools. .
- 5. Pixels The computer storesand displays pixels, or picture elements. A pixel is the smallest addressable part of the computer screen. A pixel is stored as a binary code representing a colour. The code for a pixel can have between 1 and 32 bits of binary code. 5
- 6. Pixels Example Here isthe Photoshop logo at normal size. Here it is enlarged 400% so that you can see the individual pixels. 6
- 7. Pixel Depth Pixel Depthdescribes the number of bits used to store each pixel. The greater the pixel depth, the more colours a pixel can have. Colour graphics vary in realism depending on resolution and pixel depth. The greater the pixel depth, the bigger the file. 7
- 8. Examples of PixelDepth Monochrome Monochrome graphics have one-bit pixel depth. (pure black or pure white) 8
- 9. Examples of PixelDepth Gray-Scale • Gray-Scale graphics have more bit-depth (No colours besides black, white and grey) 9
- 10. Examples of PixelDepth 8 Bit Colour • 8 bits per pixel provides 256 colour choices (Typical of the web - that’s why web graphics need some skilful preparation) 10
- 11. Examples of PixelDepth • 24 or 32 bits per pixel provides thousands or millions of colour choices. (Typical of graphics and games software) 11
- 12. How do westore this? We would like to allocate memory to hold the results of the computation stage. 12
- 13. Framebuffer Framebuffer - Ablock of memory, dedicated to graphics output, that holds the contents of what will be displayed. Pixel - one element of the framebuffer 13
- 14. 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Framebuffer Questions: • How much memory do we need to allocate for the framebuffer? • How many pixels are there? • How big is the framebuffer? • What is the largest image you can display? 14
- 15. Resolution Resolution refers tothe density of dots on the screen or printed image and directly affects quality The higher the resolution, the less jagged the image. Resolution is measured in DPI (Dots per Inch) (The printing industry is largely unmetricated and still uses inches because printing measures such as the Point (1 72nd of an inch) do not easily convert to metric units.) The higher the resolution, the better the potential output. 15
- 16. Typical Resolutions Screens generallyoperate at around 72-100 dpi Printed images range from 300 to 2400 dpi Resolution affects the file size of an image. The higher the resolution, the bigger the file. The visible resolution is limited to the maximum possible on the output device (screen or printer). No matter how high the resolution of a photograph, it will show at the resolution of your screen or printer. 16
- 17. Aspect Ratio Aspect ratio:the ratio of the rectangle’s width and height If different in Orthogonal and Window Size – undesirable side effects caused by the independence of object, viewing parameters and workstation window specifications Concept of a VIEWPORT 17
- 18. Scan Conversion (Rasterization) Convert high-level geometry description to pixel colors in the frame buffer Example: given vertex x, y coordinates determine pixel colors to draw line Two ways to create an image: – Scan existing photograph – Procedurally compute values (rendering) Viewport Transformation Rasterization 18
- 19. Rasterization A fundamentalcomputer graphics function Determine the pixels’ colors, illuminations, textures, etc. Implemented by graphics hardware Rasterization algorithms – Lines – Circles – Triangles – Polygons 19
- 20. Rasterization Operations • Drawinglines on the screen • Manipulating pixel maps (pixmaps): copying, scaling, rotating, etc • Compositing images, defining and modifying regions • Drawing and filling polygons – Previously glBegin(GL_POLYGON), etc • Aliasing and antialiasing methods 20
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