Method of color accentuation with compensation and adjustment

• US 20050213125A1
• Filed: 02/18/2005
• Published: 09/29/2005
• Est. Priority Date: 08/19/2002
• Status: Abandoned Application

• Current Assignee: Paul Reed Smith Guitars, Limited Partnership
• Original Assignee: Paul Reed Smith Guitars, Limited Partnership
• Inventors: Gilbert, Gary E., Smith, Paul Reed, Sabety, Ted
• Application Number:
  US11/060,294
• Publication Number:
  US 20050213125A1
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 5/009 Global, i.e. based on properties of the image as a whole applied in cameras using an electronic image sensor H04N23/80, H04N23/70
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence
• CPC Class Codes: H04N 1/6086 by scene illuminant, i.e. conditions at the time of picture capture, e.g. flash, optical filter used, evening, cloud, daylight, artificial lighting, white point measurement, colour temperature

Abstract

The color accentuation method determines the relative magnitude of each color component in each pixel or area. It selects and adjusts the magnitude of one or more of the colors as a function of the determined relative magnitudes of each color component. The type and amount of the adjustment is a function of the relative magnitude differences. One or more of the magnitudes is adjusted to change the relative magnitudes. Typically, the difference in a subtractive color space is between the lowest and middle magnitude color and in an additive color space is between the highest and the middle magnitude color. Also, typically, the lowest color component is reduced in the subtractive color space and the highest is increased in the additive color space. Various scaling functions and compensations or adjustments of the color accentuation may be used.

Claims

1. A method of color adjustment of a digital image comprising:

determining, for at least one pixel in a color image, which of the color components of the pixel are, relative to each other, either the maximum and middle components for an additive space or the middle and minimum magnitudes for a subtractive space; and

adjusting the magnitude of either the maximum color component by a scaling function, whose argument includes the difference of the maximum and middle component magnitudes in an additive color space, or the magnitude of the minimum color component by a scaling function, whose argument includes the difference of the middle and minimum component'"'"'s magnitudes in a subtractive color space;

wherein the absolute value of the scaling function initially increases from an initial value to a maximum value as the difference increases from its minimum to its maximum, whereby the maximum absolute value in the scaling function is reached when the value of the difference is less than its maximum range.

2. The method according to claim 1, wherein the absolute value of the scaling function initially increases from an initial value to a maximum value and finally decreases to a final value which is less than the maximum value.

3. The method according to claim 1, wherein the initial increase is between and extends over all or a portion of 0% to 50% of the range of the differences, the peak is between and extends over all or a portion of 0% to 80% of the difference range and the final decrease is between and extends over all or a portion of 40% to 100% of the difference range.

4. The method according to claim 1, wherein the initial increase is 20% to 40% of the total range of the differences, the peak is 25% to 35% of the total difference range and the final decrease is 20% to 25% of the total difference range.

5. The method according to claim 1, including determining the most dominant color component and next dominant color component in a group of pixels;

adjusting the most dominant color component as a function of a comparison of the most dominant color component to the next dominant color component.

6. The method of claim 5, where the determining step is made by calculating a convolution on all neighboring pixels within a bound area.

7. The method of claim 6, wherein the convolution is calculated for a pixel located at point x,y in the image is calculated as:

$\mathrm{Cx},y=\underset{x^{\mathrm{\prime <br><br>}}=x-x_0}{\overset{x^{\mathrm{\prime <br><br>}}=x+x_0}{\sum <br><br>}}<br><br>\underset{y^{\mathrm{\prime <br><br>}}=y-y_0}{\overset{y^{\mathrm{\prime <br><br>}}=y+y_0}{\sum <br><br>}}<br><br>\frac{\%<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{MAX}<br><br>\left(x^{\mathrm{\prime <br><br>}},y^{\mathrm{\prime <br><br>}}\right)}{{\left({\left(x^{\mathrm{\prime <br><br>}}-x\right)}^2+{\left(y^{\mathrm{\prime <br><br>}}-y\right)}^2\right)}^N}$

where % MAX(x′

,y′

) is the value of the color component being analyzed at point (x′

,y′

) in the image, X₀,Y₀ are the dimensions of the region of convolution, and N is the selected sharpness of the convolution function.

8. The method according to claim 1, including after the magnitude adjusting, determining the brightness of the color components before and after the magnitude adjustment;

and adjusting some of the color components as a function of the comparison of the before and after brightnesses.

9. A color accentuation method for a pixel of a digital color image comprising:

calculating either a new maximum color component value of the pixel as a function of the maximum color component for that pixel and the value of the same color component among a pre-determined number of local pixels for an additive color space or a new minimum color component value of the pixel as a function of the minimum color component for that pixel and the value of the same color component among a pre-determined number of local pixels for a subtractive color space;

calculating a scaling function using either the calculated new maximum color component value for the additive color space or the new minimum color component value for the subtractive color space; and

adjusting the value of either the new maximum color component for the additive color space or the new minimum color component value for the subtractive color space of the pixel by the amount of the scaling function.

10. A method of color adjustment of a digital image made up of pixels residing in a color signal processing system comprising:

increasing the saturation of at least one color component in at least one pixel whose position on a color wheel lies substantially within an annular ring around the center of the color wheel while not substantially increasing the saturation of said at least one color component for the pixel that lies outside the annular ring.

11. A method of color adjustment of a digital image made up of pixels encoded in a polar color space, residing in a color signal processing system comprising:

determining for at least one pixel in the image the difference of the amount of at least two of the set of red, green, blue and yellow by calculating a linear combination of at least two of the polar color components of said pixel.

12. A method of color adjustment of a digital image made up of pixels encoded in a polar color space, residing in a color signal processing system comprising:

determining for at least one pixel in the image, the maximum, middle and minimum amounts of three of the set of red, green, blue and yellow; and

adjusting the apparent intensity of at least one of the set of red, green, blue and yellow by calculating new values for the polar color components as a function of the difference between said maximum and middle amounts.

13. A method of color accentuation comprising:

determining, for at least one pixel in a color image, the relative magnitude of each color component of the pixel;

determining, for a subtractive color space, the difference of the magnitude of a middle color component to a lowest color component and, for an additive color space, the difference of the magnitude of a highest color component to a middle color component; and

selecting and adjusting the magnitude of one or more of the color components of the pixel by an amount that is a function of the determined difference of the middle color component to the lowest color component for the subtractive color space and a degree of whiteness and is a function of the determined difference of the highest color component to the middle color component for the additive color space and a degree of whiteness.

14. A system for receiving input signal for an image to be displayed in color, the system including a signal processor and wherein the signal processor:

receives or derives color components of a pixel from the input signals;

determines for a subtractive or an additive color space the relative magnitude of each color component of the pixel;

determines, for the subtractive color space, the difference of the magnitude of a middle color component to a lowest color component and, for the additive color space, the difference of the magnitude of a highest color component to a middle color component; and

selects and adjusts the magnitude of one or more of the color components as a function of the determined difference of the middle color component to the lowest color component for the subtractive color space and a degree of whiteness and as a function of the determined difference of the highest color component to the middle color component for the additive color space and a degree of whiteness.

15. A method of color accentuation of a color image made up of areas, encoded in a color space, the method comprising:

detecting in each area the magnitude of each color component of the color space; and

adjusting the magnitude of color components in each area in accordance with a scaling function applied to the detected color components to increase the difference between a maximum and a minimum color component in each area, the scaling function being based on a difference of a middle color component to the lowest color component for a subtractive color space and a degree of whiteness or on a difference of the highest color component to the middle color component for an additive color space and a degree of whiteness for each area.

16. A color accentuation method for a pixel comprising:

calculating a maximum color component value of the pixel as a function of the maximum color component for that pixel and the value of the same color component among a pre-determined number of local pixels;

calculating a scaling function using the calculated maximum color component value; and

adjusting the value of the color component of the pixel by the amount of the scaling function.

17. A method of color accentuation comprising:

determining, for at least one pixel in a color image, the relative magnitude of each color component of the pixel;

determining, for a subtractive color space, the difference of the magnitude of a middle color component to a lowest color component and, for an additive color space, the difference of the magnitude of a highest color component to a middle color component; and

selecting and adjusting the magnitude of one or more of the color components of the pixel by an amount that is a function of the determined difference of the middle color component to the lowest color component for the subtractive color space and the value of the lowest color component and is a function of the determined difference of the highest color component to the middle color component for the additive color space and the value of the highest color component.

18. A method of color accentuation comprising:

determining, for at least one pixel in a color image, the relative magnitude of each color component of the pixel;

determining, for a subtractive color space, the difference of the magnitude of a middle color component to a lowest color component and, for an additive color space, the difference of the magnitude of a highest color component to a middle color component; and

selecting and adjusting the magnitudes of the lowest and middle color components of the pixel by an amount that is a function of the determined difference of the middle color component to the lowest color component for the subtractive color space and the magnitudes of the highest and middle color components of the pixel by an amount that is a function of the determined difference of the highest color component to the middle color component for the additive color space.

19. A method of color accentuation comprising:

determining, for at least one pixel in a color image, the relative magnitude of each color component of the pixel;

determining, for a subtractive color space, the difference of the magnitude of a middle color component to a lowest color component and, for an additive color space, the difference of the magnitude of a highest color component to a middle color component;

selecting and adjusting the magnitude of one or more of the color components of the pixel by an amount that is a function of the determined difference of the middle color component to the lowest color component for the subtractive color space and is a function of the determined difference of the highest color component to the middle color component for the additive color space; and

equalizing the pixels in the image using histogram equalization at least once during the method.

20. A method of contrast enhancement of a color image comprising:

transforming the color components of the color image into a set of gray scale levels, the magnitude of the color components have one of a first number of values and the gray scale levels have one of a second number of values substantially greater than the first number of values;

enhancing the pixels in the image using histogram equalization of the gray scale image.

21. A method of contrast enhancement of a color image comprising:

transforming the color components of the color image into a gray scale image;

selecting a scaling factor which determines the amount of equalization; and

enhancing pixels of the color image using histogram equalization of the gray scale image using the selected scaling factor.