Adaptive linear contrast method for enhancement of low-visibility imagery

A non-transitory computer readable storage medium having a method encoded thereon, the method represented by computer readable programming code, the method comprising the steps of:

• segmenting an image into a plurality of tiles;
• calculating an upper clip limit and a lower clip limit for each tile of the plurality of tiles based upon a user input standard deviation, wherein
• if the user input standard deviation is zero, then determining a tile mean and a tile standard deviation, if the tile standard deviation is less than about 0.03, then incrementing a standard deviation number by one, if the tile standard deviation is less than about 0.005, then further incrementing the standard deviation number by one, if the tile mean is less than about 0.4, then setting the lower clip limit to about 0.0011 and the upper clip limit to about the tile mean plus the product of the standard deviation number and the tile standard deviation, if the tile mean is greater than about 0.6, then setting the upper clip limit to about 0.99 and the lower clip limit to about the tile mean minus the product of the standard deviation number and the tile standard deviation, and if the tile mean is greater than or equal to about 0.4 and less than or equal to about 0.6, and the tile standard deviation is less than or equal to about 0.15, then setting the standard deviation number to two, setting the lower clip limit to about the tile mean minus the product of the standard deviation number and the tile standard deviation, and setting the upper clip limit to about the tile mean plus the product of the standard deviation number and the tile standard deviation,
• if the user input standard deviation is greater than zero, then determining a tile mean and a tile standard deviation, setting the lower clip limit to about the tile mean minus the product of the standard deviation number and the tile standard deviation, and setting the upper clip limit to about the tile mean plus the product of the standard deviation number and the tile standard deviation;
• generating a lookup table for each tile of the plurality of tiles by linearly mapping the input pixel values of the image to the output pixel values of the image based upon the calculated upper clip limit and lower clip limit;
• processing each tile of the plurality of tiles based upon the generated lookup table;
• and generating a processed image by combining each of the processed tiles.

A system comprising:

• a display;
• a processor operatively connected to the display;
• and
• a memory module operatively connected to the processor, the memory module having program instructions stored therein, wherein the program instructions are executable by the processor to perform a method comprising the steps of:
• segmenting an image into a plurality of tiles;
• calculating an upper clip limit and a lower clip limit for each tile of the plurality of tiles based upon a user input standard deviation, wherein
• if the user input standard deviation is zero, then determining a tile mean and a tile standard deviation, wherein if the tile standard deviation is less than about 0.03, then incrementing a standard deviation number by one, if the tile standard deviation is less than about 0.005, then further incrementing the standard deviation number by one, if the tile mean is less than about 0.4, then setting the lower clip limit to about 0.0011 and the upper clip limit to about the tile mean plus the product of the standard deviation number and the tile standard deviation, and if the tile mean is greater than about 0.6, then setting the upper clip limit to about 0.99 and the lower clip limit to about the tile mean minus the product of the standard deviation number and the tile standard deviation,
• if the user input standard deviation is greater than zero, then determining a tile mean and a tile standard deviation, setting the lower clip limit to about the tile mean minus the product of the standard deviation number and the tile standard deviation, and setting the upper clip limit to about the tile mean plus the product of the standard deviation number and the tile standard deviation;
• and
• generating a lookup table for each initial tile by linearly mapping the input pixel values of the image to the output pixel values of the image based upon the calculated upper clip limit and lower clip limit.