Adaptive pixel-level color enhancement for a digital camera

Abstract

An adaptive color enhancer applies different scale factors to different pixels in a digital image. More color enhancement occurs for bright pixels and for dim pixels than for average-intensity pixels. Also, more color enhancement is applied to the more colorful pixels while less color enhancement is applied to dull, less-colorful pixels. Rather than enhance all pixels to the same extent, the bright, colorful pixels are enhanced further than the average. Likewise, dim areas are color enhanced more than average. A calculation unit receives a YUV pixel. The Y value is compared to range limits and a piece-wise-linear (PWL) function generates an intermediate scale factor. The absolute values of the U and V color values are combined to create a colorfulness factor. The colorfulness factor is also used with a PWL function and the intermediate scale factor to generate a final scale factor for that pixel. The final scale factor is then multiplied by the U and V values of the pixel to generate a color-corrected pixel.

Description

FIELD OF THE INVENTION[0001]This invention relates to digital cameras, and more particularly for color enhancement of a digital image.BACKGROUND OF THE INVENTION[0002]Family photos in color replaced earlier black-and-white photographs in the 1960's. More recently, digital cameras are replacing traditional film cameras. Digital cameras are being improved and lowered in cost at a rapid pace. Images from digital cameras can be downloaded and stored on personal computers. Digital pictures can be converted to common formats such as JPEG and sent as e-mail attachments or posted to virtual photo albums on the Internet. Video as well as still images can be captured, depending on the kind of digital camera.[0003]Bright, rich colors in pictures are still preferred, even for digital pictures. Color enhancement can be applied to digital pictures as it has been applied in wet photofinishing processes for traditional cameras. For digital pictures, each picture dot (pixel) is originally represente...

AI Technical Summary

Benefits of technology

[0017]An applicator receives the current pixel value from the pixel input. It applies the enhancement factor from the calculation unit to the current pixel value to generate an enhanced pixel value. The enhanced pixel value is output in place of the current pixel value. Thus pixels are color enhanced using the enhancement factor generated from the current pixel value.

Problems solved by technology

This can sometimes produce an undesirable color saturation effect, where the image is too bright and has too much color in it.

Images