Tone mapping with adaptive slope for image sharpening

A method for sharpening a captured image having a plurality of pixels using a processor to perform the following steps:

• identifying a plurality of edge pixels in the captured image;
• reviewing the plurality of edge pixels to identify one or more line edge pixels in the captured image, and one or more step-like edge pixels in the captured image;
• selecting one of the step-like edge pixels;
• normalizing an intensity value for the selected step-like edge pixel;
• determining an adjusted normalized intensity value for the selected step-like edge pixel using the normalized intensity value for the selected step-like edge pixel and a first contrast correction function having a first slope;
• selecting one of the line edge pixels;
• normalizing an intensity value for the selected line edge pixel;
• and
• determining an adjusted normalized intensity value for the selected line edge pixel using the normalized intensity value for the selected line edge pixel and a second contrast correction function having a second slope that is different than the first slope.

A method for sharpening a captured image using a processor to perform the following steps:

• processing a first pixel in the captured image that includes a plurality of first neighboring pixels that are positioned in a predetermined first pixel window by (i) identifying a first intensity value for the first pixel;
• (ii) selecting a first selected high intensity value for the first pixel window;
• (iii) selecting a first selected low intensity value for the first pixel window;
• (iv) normalizing the first intensity value to establish a first normalized intensity value using the selected high intensity value and the selected low intensity value;
• (v) determining a first adjusted normalized intensity value for the first normalized intensity value using a first contrast correction function having a first slope in a middle;
• and (vi) scaling the first adjusted normalized intensity value to get a first transformed intensity value;
• and
• processing a second pixel in the captured image that includes a plurality of second neighboring pixels that are positioned in a predetermined second pixel window by (i) identifying a second intensity value for the second pixel;
• (ii) selecting a second selected high intensity value for the second pixel window;
• (iii) selecting a second selected low intensity value for the second pixel window;
• (iv) normalizing the second intensity value to establish a second normalized intensity value;
• (v) determining a second adjusted normalized intensity value for the second normalized intensity value using a second contrast correction function having a second slope in a middle that is different than the first slope;
• and (vi) scaling the second adjusted normalized intensity value to get a second transformed intensity value.