This algorithm is used, in compression mode 0, in conforming PNG datastreams . Deflate is a member of the LZ77 family of compression methods. 3.18 display image image constructed for display from a decoded PNG datastream . 3.19 filter transformation applied to an array of scanlines with the aim of improving their compressibility. 3.20 frame buffer the final digital storage area for the image shown by most types of computer display.
Software causes an image to appear on screen by loading the image into the frame buffer.
3.21 gamma exponent that describes approximations to certain non-linear transfer functions encountered in image capture and reproduction. 3.23 image data 1-dimensional array of scanlines within an image. 3.24 implied alpha implicit representation of the alpha channel . If every pixel is fully opaque the alpha channel can be implied by the colour type and is not stored explicitly as part of the image data. 3.25 indexed-colour image representation in which each pixel of the original image is represented by a single index into a palette .