Image background enhancement for color images

A computer-implemented method of enhancing the background of an original document image with a colored background, comprising:

• obtaining color image histograms of red, blue and green colors of the original document image;
• smoothing said histograms;
• comparing the smoothed histograms to determine if they have the same shape;
• if the histograms have the same shape, detecting the background color of the original document image for each color channel in a first way, while if the histograms do not have the same shape, detecting the background color of the original document image for each color channel in a second way;
• determining the desired enhanced background color of the original document image;
• and
• enhancing the original document image to the desired enhanced background color.

A computer readable storage medium containing instructions stored thereon that when processed by a processor cause said processor to implement a method of enhancing the background of an original document image, the instructions comprising instructions for:

• detecting the background color of the original document image;
• determining the desired enhanced background color of the original document image from a background pixel value Pb that is in the center of the background color range;
• and
• enhancing the original document image to the desired enhanced background color.

A computer readable storage medium containing instructions stored thereon that when processed by a processor cause said processor to implement a method of enhancing the background of an original document image having a colored background, the instructions comprising instructions for:

• obtaining color image histograms of red, blue and green colors of the original document image;
• smoothing said histograms;
• comparing the smoothed histograms to determine if they have the same shape;
• if the histograms have the same shape, detecting the background color of the original document image for each color channel in a first way, while if the histograms do not have the same shape, detecting the background color of the original document image for each color channel in a second way;
• determining the desired enhanced background color of the original document image;
• and
• enhancing the original document image to the desired enhanced background color.

The medium of claim 32, wherein the instructions for determining the desired enhanced background color Peb of the original document image comprises instructions for:

• if Peb for a red, green, or blue color channel has a value of N, generating a look-up table LT as follows, where i is the image pixel value of a specific color channel that is in the range [0, N], B is a small value that can always be safely set to pure black value 0, and Plb takes the value of PlbRed, PlbGreen or PlbBlue depending on the color channel:
• LT
• 
• (
• i
• )
• =
• {
• 0
• i
• ≤
• B
• N
• i
• ≥
• P
• lb
• N
• ·
• (
• i
• -
• B
• )
• P
• lb
• -
• B
• Otherwise
• ;
• if Peb for the red, green or blue color channel does not have a value of N, generating a look-up table LT as follows, where Prb takes the value of PrbRed, PrbGreen or PrbBlue depending on the color channel:
• LT
• 
• (
• i
• )
• =
• {
• P
• eb
• if
• 
• 
• P
• lb
• ≤
• i
• ≤
• P
• rb
• i
• Otherwise
• ;
• and
• enhancing the image background such that for each image pixel with value p in a specific color channel of the original document image the pixel value is changed from p to LT(p) in that channel.