A method for determining whether an input image is defined in accordance with a luminance-chrominance color space, includes receiving an input image in three dimensional color space, S1, S2 and S3, where S1 is an image value in the first dimension, S2 is an image value in the second dimension and S3 is an image value in the third dimension; extracting low and high extrema of S1 values in the image; obtaining deviation of S2 and S3 from a predefined neutral axis for all pixels in the image whose S1 value is either the low or the high extremum; testing a condition that certain of the deviations are within predetermined thresholds; and determining, if the condition holds true, that the image is in a luminance-chrominance color space.