Patent ID: 9489344
Filing Date: 2016-11-08
CPC Classification: G06F

Claim Text:
1. A processor-implemented method of converting an input graphics data value to an output graphics data value by approximating a function that maps input values to output values, the processor comprising processing circuitry including a bit shift circuit, a dedicated divide by 3 circuit, and a dedicated divide by 5 circuit, the method comprising: deriving a first value from the input graphics data value, wherein the first value is within a predetermined first range of values, the first range of values being quantised into a first set of plural range sections, wherein each range section of the first set of plural range sections comprises a first predetermined section end value; and converting the first value into a second value that is within a predetermined second range of values, the second range of values being quantised into a second set of plural range sections, wherein each range section of the second set of plural range sections comprises a second predetermined section end value, wherein each range section of the second set of plural range sections corresponds to a range section of the first set of plural range sections such that there are respective pairs of corresponding first and second range sections, wherein each pair of corresponding first and second range sections is associated with a gradient, the gradient for each pair of corresponding first and second range sections approximating the gradient of the function for that pair of corresponding first and second range sections, wherein the gradients for the pairs of corresponding first and second range sections are gradient values selected from the set consisting of: 3*2^n; 4*2^n; and 5*2^n; where n is a non-negative integer, wherein the step of converting the first value into the second value comprises: determining by reference to a look-up table that is stored in memory or that is accessed using a set of logical operations or nested set of comparators a first predetermined section end value for a first range section of the first set of plural range sections within which the first value lies, identifying by reference to the look-up table a second predetermined section end value for a second range section of the second set of plural range sections that corresponds to the first range section, identifying by reference to the look-up table the gradient associated with the pair of corresponding first and second range sections, and converting the first value into the second value using the first section end value, the second section end value and the gradient, wherein using the gradient comprises using the bit shift circuit when dividing by 2, the dedicated divide by 3 circuit when dividing by 3, and the dedicated divide by 5 circuit when dividing by 5; the method further comprising: deriving the output graphics data value from the second value; and providing a graphics output for display based on the output graphics data value.