A processing for a first pixel in a picture comprises setting upper and/or lower limits of a first color component of the first pixel in a first color space to a respective fixed value if a maximum and/or minimum value of the first color component in the first color space results in a color component in a second color space that is below a first value of the color component in the second color space and above a second value of the color component in the second color space. A filtered value is obtained of the first color component and which is equal to or larger than the lower limit and equal to or lower than the upper limit. The processing results in filtered values that are cheaper to encode but that are visibly undistinguishable from the original colors of the pixels.