Look-up table based gamma and inverse gamma correction for high-resolution frame buffers

A method of operating an image display system, comprising the steps of:

• generating image pixel data wherein each pixel has an M-bit value within a first non-linear range of values;
• converting each of the M-bit pixel values to an N-bit pixel value within a linear range of values;
• storing the N-bit pixel values;
• and
• converting N-bit pixel values output by said storage means to P-bit pixel values within a second non-linear range of values.

An image display system comprising:

• a source of inverse gamma corrected image pixel data wherein each pixel is expressed with M-bits;
• means, coupled to an output of said source, for gamma correcting each of said M-bit pixel values to an N-bit value within a linear range of values;
• frame buffer means, having an input coupled to an output of said first converting means, for storing the gamma converted N-bit pixel values;
• means, coupled to an output of said frame buffer means, for inverse gamma correcting N-bit pixel values output by said frame buffer means to P-bit pixel values;
• and
• means, coupled to an output of said inverse gamma correcting means, for converting the P-bit pixel data to an analog voltage for driving a CRT-display means.

An image display system comprising:

• a source of image pixel data wherein each pixel has an M-bit value within a non-linear range of values;
• first means, coupled to an output of said source, for converting each of said M-bit pixel values to an N-bit value within a linear range of values;
• storage means, having an input coupled to an output of said first converting means, for storing the N-bit pixel values;
• and
• second means, coupled to an output of said storage means, for converting N-bit pixel values output by said storage means to P-bit pixel values within a non-linear range of values, said second means converting the N-bit pixel values prior to an application of said converted P-bit pixel values to a display means;
• wherein
• P and N are both related to an expression E=[S(e).sup.1/y /S].sup.y, where E is a video signal voltage and where y is a power function exponent, both of which are associated with the display means, and where the coefficient S satisfies the following relations:
• O=INT[P-1)(I/N-1).sup.1/y +0.5] and
• I=INT[(N-1)(O/P-1).sup.y +0.5],
• where N=a number of linear input (I) levels, P=a number of gamma corrected output (O) levels, (I/N-1) and (O/P-1) are normalized input and output values, respectively, S=P-1, and INT is a truncating integer function.