Method and apparatus for modifying the color saturation of electronically acquired images
AssigneeInstitut für Mikroelecktronik Stuttgart
InventorsBernd Hofflinger, Heinz Gerhard Graf
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Abstract
A method for the transformation of image signals that have been obtained by color filtering and have been logarithmically compressed is proposed. The color saturation of the recorded images is increased thereby. According to one aspect of the invention, the transformed image signals are determined as a function of the logarithmically compressed image signals and the logarithmically compressed brightness signals for a spectral color.
Claims14
In a digital camera comprising an electronic image recorder for recording an overall image signal, said image recorder comprising a regular arrangement of pixels, each pixel having three light-sensitive image cells each covered by one of three different color filters, and each pixel thus generating three mutually independent image signals assigned to one of three colors, wherein said overall image signal comprises a color saturation, a method for modifying said color saturation, said method comprising the steps of:
- recording said mutually independent image signals in each of said pixels in a logarithmically compressed format,
- determining a logarithmically compressed brightness signal from said mutually independent image signals as an arithmetic mean of said mutually independent image signals,
- selecting at least one of said mutually independent image signals, and
- transforming said at least one independent image signal selected as a function of said logarithmically compressed brightness signal.
A method of modifying a color saturation in an overall image signal comprising mutually independent image signals assigned to one of three different colors, said method comprising the steps of:
- providing said mutually independent image signals in a logarithmically compressed format,
- determining a logarithmically compressed brightness signal from said mutually independent image signals,
- selecting the independent image signal of at least one color, and
- transforming said independent image signal selected as a function of said logarithmically compressed brightness signal.
A digital camera comprising:
- an electronic image recorder for recording an overall image signal having a color saturation, said image recorder comprising a regular arrangement of pixels, each pixel having three light-sensitive image cells covered by one of three different color filters, and each pixel thus generating three mutually independent image signals assigned to one of three colors, said pixels generating said mutually independent image signals in a logarithmically compressed format, and
- a saturation stage for modifying said color saturation, said saturation stage comprising a digital signal processor adapted to execute a method comprising the steps of:
- determining a logarithmically compressed brightness signal from said mutually independent image signals,
- selecting the independent image signal for at least one color, and
- transforming said independent image signal selected as a function of said logarithmically compressed brightness signal.
A saturation stage for modifying a color saturation of an overall image signal comprising logarithmically compressed and mutually independent image signals assigned to one of three different colors, said saturation stage comprising a computer adapted to execute a method comprising the steps of:
- determining a logarithmically compressed brightness signal from said mutually independent image signals,
- selecting the logarithmically compressed independent image signal for at least one color, and
- transforming said logarithmically compressed independent image signal determined as a function of said logarithmically compressed brightness signal.
Dependencies are inferred from the claim text.