A method and apparatus for converting a color digital image into a grayscale digital image is disclosed. First, each green intensity value in the color digital image is copied into a corresponding pixel location of the grayscale digital image. Then for each red intensity value in the color digital image, the red intensity value is adjusted to match a local dynamic range of green intensity values. The adjusted red intensity value is inserted into the corresponding pixel location of the grayscale digital image. Then for each blue intensity value in the color image, the blue intensity value is adjusted to match a local dynamic range of green intensity values. The adjusted blue intensity value is inserted into the corresponding pixel location of the grayscale digital image.