Method and system of image capture based on logarithmic conversion

Abstract

Image capture based on logarithmic conversion. At least some of the illustrative embodiments are methods including capturing an image by: reading a plurality of analog signals from an array of light sensitive elements; performing logarithmic analog-to-digital conversion on the plurality of analog signals which creates a corresponding plurality of digital values; calculating a dynamic range of the image, the calculating by a processor executing a program; adjusting at least one of a brightness and contrast of the image based on the dynamic range; further adjusting at least one of the brightness and contrast by a user by way of an interface device; and storing representations of the plurality of digital values to a storage medium wherein the representations of the digital values include the image brightness and contrast adjustments.

What is claimed is: 
     
         1 . A method comprising:
 capturing an image by
 reading a plurality of analog signals from an array of light sensitive elements; 
 performing logarithmic analog-to-digital conversion on the plurality of analog signals which creates a corresponding plurality of digital values, each corresponding to a digital luminance value; 
 calculating a dynamic range of the image, the calculating performed by a processor executing a program; 
 adjusting at least one of a brightness and contrast of the image based on the dynamic range; 
 further adjusting at least one of the brightness and contrast of the image by a user by way of an interface device; and 
   storing representations of the plurality of digital values to a storage medium, wherein the representations of the digital values include the image brightness and contrast adjustments.   
     
     
         2 . The method of  claim 1  wherein performing logarithmic analog-to-digital conversion further comprises:
 performing piecewise logarithmic analog-to-digital conversion by
 sequentially applying each analog signal to a first linear analog-to-digital converter and simultaneously applying to a second linear analog-to-digital converter distinct from the first linear analog-to-digital converter; 
 reading a first portion of the plurality of digital values from the first linear analog-to-digital converter; and 
 reading a second portion of the plurality of digital values from the second linear analog-to-digital converter. 
 
 
     
     
         3 . The method of  claim 1  wherein storing representations of the plurality of digital values further comprises storing, for each digital value, a combination of a value indicative of an octave and a value indicative of gradation within the octave. 
     
     
         4 . The method of  claim 4  wherein storing representations of the plurality of digital values further comprises storing, for at least one digital value, a combination of a value indicative of an octave, a value indicative of gradation within the octave, and a value indicative of a color. 
     
     
         5 . The method of  claim 1  wherein capturing the image further comprises capturing by at least one selected from the group consisting of: a mobile device; a mobile cellular device; a scanner; a copier; and a digital camera. 
     
     
         6 . The method of  claim 1  wherein reading further comprising reading from at least one selected from the group consisting of: an array of charge coupled devices (CCD); an array of complementary metal oxide semiconductor (CMOS) devices. 
     
     
         7 . The method of  claim 1  wherein calculating a dynamic range comprises:
 locating a pixel in the image having a highest digital luminance value, the locating by a processor executing a program; 
 locating a pixel in the image having a lowest digital luminance value, the locating by a processor executing a program; and wherein:
 adjusting the brightness comprises: 
 calculating an initial value of a key value based on the highest and lowest digital luminance values, the calculating by a processor executing a program; 
 adjusting the brightness of the image based on the initial value of the key value so that after adjustment of the brightness a final value of the key value is within a predetermined range of values. 
 
 
     
     
         8 . The method of  claim 7  wherein the first key value comprises an average of the highest and lowest digital luminance values. 
     
     
         9 . A system comprising:
 a processor;   a program memory coupled to the processor, the program memory being a non-transitory computer-readable storage medium;   an array of light sensitive elements;   a user interface device coupled to the processor;   logarithmic analog-to-digital conversion circuitry that defines an analog side and a digital side, circuitry coupled to the processor on the digital side; and   an image memory coupled to the processor;   wherein the program memory stores a program that, when executed by the processor, causes the processor to capture an image by causing the processor to:
 read a plurality of digital values corresponding to a signal associated with each light sensitive element; 
 calculate a dynamic range of the image; 
 adjust at least one of brightness and contrast of the image based on the calculated dynamic range; 
 further adjust at least one of the brightness and contrast of the image by way of user input from the user interface device; and 
 store a representation of the plurality of digital values to the image memory, wherein the representation of the plurality of digital values includes the image brightness and contrast adjustments. 
   
     
     
         10 . The system of  claim 9  wherein the analog-to-digital conversion circuitry comprises:
 an amplifier coupled to the array of light sensitive devices, the amplifier producing an analog output signal logarithmically related to an analog input signal; and 
 a linear analog-to-digital converter (ADC). 
 
     
     
         11 . The system of  claim 9  wherein the analog-to-digital conversion circuitry comprises:
 an amplifier coupled to the array of light sensitive devices, the amplifier producing an analog output signal linearly related to an analog input signal; and 
 a logarithmic analog-to-digital converter (ADC) coupled to the analog output signal of the amplifier. 
 
     
     
         12 . The system of  claim 9  wherein the analog-to-digital conversion circuitry comprises:
 a first linear analog-to-digital converter (ADC) coupled to the array of light sensitive devices; and 
 a second linear analog-to-digital converter (ADC) coupled to the array of light sensitive devices, the second linear analog-to-digital converter distinct from the first linear analog-to-digital converter; 
 wherein when the processor reads a plurality of digital values corresponding to a signal associated with each light sensitive element, the program further causes the processor to:
 read a first portion of the plurality of digital values from the first linear analog-to-digital converter; and 
 read a second portion of the plurality of digital values from the second linear analog-to-digital converter based on predetermined threshold of a digital luminance value. 
 
 
     
     
         13 . The system of  claim 9  wherein when the processor stores the representation of the plurality of digital values to the image memory, the program causes the processor, for at least one digital value, to:
 store a first value in the image memory, the first value indicative of an octave; and 
 store a second value in the image memory, the second value indicative of a gradation within the octave. 
 
     
     
         14 . The system of  claim 9  wherein when the processor stores the representation of the plurality of digital values to the image memory, the program causes the processor, for each digital value, to store a value indicative of a color associated with the digital value. 
     
     
         15 . The system of  claim 9  wherein when the processor calculates the dynamic range, the program causes the processor to:
 locate a pixel in the image having a lowest digital luminance value; 
 locate a pixel in the image having a highest digital luminance value and wherein: 
 when the processor adjusts the brightness, the program causes the processor to:
 calculate an initial value of a key value based on the highest and lowest digital luminance values; and 
 adjust the brightness of the image based on the initial value of the key value so that after adjustment of the brightness, a final value of the key value is in a predetermined range of values. 
 
 
     
     
         16 . A system comprising:
 a processor;   a program memory coupled to the processor, the program memory being a non-transitory computer-readable storage medium;   an array of light sensitive elements;   a user interface device coupled to the processor;   logarithmic analog-to-digital conversion circuitry that defines an analog side and a digital side, circuitry coupled to the processor on the digital side; and   an image memory coupled to the processor;   wherein the program memory stores a program that, when executed by the processor, causes the processor to capture an image by causing the processor to:
 read a plurality of digital values corresponding to a signal associated with each light sensitive element; and 
   store a representation of the plurality of digital values to the image memory, wherein when the processor stores the representation of the plurality of digital values to the image memory, the program causes the processor, for at least one digital value, to:
 store a first value in the image memory, the first value indicative of an octave; and 
 store a second value in the image memory, the second value indicative of a gradation within the octave. 
   
     
     
         17 . The system of  claim 16  wherein the analog-to-digital conversion circuitry comprises:
 a first linear analog-to-digital converter (ADC) coupled to the array of light sensitive devices; and 
 a second linear analog-to-digital converter (ADC) coupled to the array of light sensitive devices, the second linear analog-to-digital converter distinct from the first linear analog-to-digital converter; 
 wherein when the processor reads a plurality of digital values corresponding to a signal associated with each light sensitive element, the program further causes the processor to:
 read a first portion of the plurality of digital values from the first linear analog-to-digital converter; and 
 read a second portion of the plurality of digital values from the second linear analog-to-digital converter based on predetermined threshold of a digital luminance value. 
 
 
     
     
         18 . The system of  claim 16  further comprising:
 a user interface device coupled to the processor; wherein:
 the program, when executed by the processor further causes the processor to adjust at least one of the brightness and contrast of the image by way of user input from the user interface device.