Commonly Used Image File Formats
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The document provides a comprehensive overview of image file formats including their types, compression methods, and key characteristics. It distinguishes between bitmap, vector, and metafile graphics, and discusses popular formats such as JPEG, PNG, and GIF, including their advantages and limitations. The conclusion suggests that PNG is likely to replace GIF in the future, while JPEG remains preferred for photographic images due to its efficient compression abilities.
Commonly Used Image File Formats
- 1. Fatih Özlü Image File Formats
- 2. Content Introduction to Image File Formats Image FileTypes (Bitmap/Vector) KeyTerms for Images Pixels Pixel Depth Compression Methods: Lossy-Lossless Common Image File formats JPEG PNG GIF BMP Conclusion
- 3. Why so many Image File Formats? … - BMP – PBM – TGA – TIFF – GIF – JPEG – PSD – DXF – CGM – PNG – SVG – RAW – WPG – FITS –PCX– PCD – RAS – TGA – BPS – EPS – PDF – PCT – WBM – FITS – XBM – VFF – RIB – PCX – DMP – AVS – IMG – ICO – JFIF – IFF –WMF - …
- 4. Image File Types Bitmap(Raster) images: collection of dots each pixel can hold 1,8,24,… bit of color information fixed resolution best for photographic quality images, for printing, scanners, digital cameras examples: bmp, gif, png, jpeg, tiff, … Vector graphics: based on mathematical instructions basically defined by shapes and lines not resolution dependent: infinitely scalable examples: svg, ai, wmf, … Metafile graphics: combination of bitmap and vector
- 5. Pixels image elements smallest addressable part of the screen stored as a binary code representing a color between 1 and 32 bits of binary code RGB (Red, Green Blue) CMYK (Cyan, Magenta,Yellow, Black) resolution density of dots on image measured in DPI (dots per Inch)
- 6. Pixel Depth Images retrieved from http://en.wikipedia.org/ number of bits to store each pixel greater depth, more colors greater depth, bigger file size monochrome : 1 bit(white and black) grayscale, 16, 256 color truecolor: 24 bit 1 bit 2 bit 4 bit 8 bit 24 bit
- 7. Compression large amount of data lossy/lossless quality Some algorithms LZW(Lemple-Zif –Welch)Algorithm RLEAlgorithm ZIP Compression JPEG Compression -> lossy Deflation – used in PNG, MNG, andTIFF
- 8. JPEG (Joint Photographic Experts Group) most applications and browsers, digital cameras good compression algorithm : reduce file size in a ratio between 10:1 and 20:1. degree of compression is adjustable lossy compression not support transparent color not interlaced:??? extensions: .jpeg, .jpe, .jpg, .jif, .jfif, .jfi Higher quality (Q = 100) High quality (Q = 50) Medium quality (Q = 25) Low quality (Q = 10) Lowest quality (Q = 1) 83,261 bytes 15,138 bytes 9,553 bytes 4,787 bytes 1,523 bytes the uncompressed 24-bit RGB bitmap image below 313 × 234 image (73,242 pixels) would require 219,726 bytes
- 9. GIF (Graphics Interchange Format) most widely used few colors: 8 bit or less LZW lossless compression algorithm less space, less loading time interlaced and non-interlaced supports animation: can contain more than one image LZW algorithm patent issue resulted PNG.
- 10. PNG (Portable Network Graphics) developed due to legal problems with compression algorithm PNG's Not GIF new format targeted for Internet use, becoming common lossless compression (more than GIF, less than JPEG) 24-bit RGB, 32-bit RGBA or up to 48 bit color transparency (A:Alpha channel) no animation support better interlacing: Adam7 algorithm Illustration of the 7 passes of the Adam7 algorithm, running over a 16×16 image
- 11. BMP (Bitmap Image File) Microsoft native image format Windows,OS/2, no MAC compatibility. backgrounds, graphics, wallpaper 1(monochrome), 4, 8, 24-bit RGB generally uncompressed, too large size lossless RLE compression
- 12. Conclusion compression larger file, larger storage and slower download few color, smaller file, worse quality There is really no reason to ever use this format BMP GIF and JPG are the formats used for nearly all web images. PNG is supported by most of the latest generation browsers. But Microsoft Internet Explorer does not support PNG transparency. PNG does everything GIF does, and better, so expect to see PNG replace GIF in the future. PNG will not replace JPG, since JPG is capable of much greater compression of photographic images, even when set for quite minimal loss of quality