A method comprising: receiving encoded digital image data for a still image, wherein the still image is encoded using a reversible lapped transform, the encoded digital image data comprising downsampled chroma information; decoding chroma position information for the downsampled chroma information, wherein the chroma position information is signaled in an image header, wherein the chroma position information is determined according to a chroma position rule that maps the chroma position information to phase information in an X dimension and phase information in a Y dimension, wherein the chroma position rule maps the chroma position information to phase information that include phase positions -0.5, -0.25, 0, 0.25, 0.5, 0.75, 1, 1.25 and 1.5, where the phase positions are in pixel units, wherein the decoding of the chroma position information comprises decoding a first syntax element that represents the phase information in the X dimension and a second syntax element that represents the phase information in the Y dimension; performing a rotation or flipping operation to the encoded digital image data while the still image is in the compressed domain, including performing the flipping operation by modifying transform coefficients in transform blocks generated using the reversible lapped transform or performing the rotation operation by modifying and transposing the transform coefficients in the transform blocks, wherein the modifying the transform coefficients comprises negating the sign of odd-symmetric transform coefficients in the transform blocks, and modifying the chroma position information to reflect the rotation or flipping operation; decoding the still image from the encoded digital image data using an inverse of a the reversible lapped transform; and outputting a decoded still image. receiving encoded digital image data for a still image, wherein the still image is encoded using a reversible lapped transform, the encoded digital image data comprising downsampled chroma information; decoding chroma position information for the downsampled chroma information, wherein the chroma position information is signaled in an image header, wherein the chroma position information is determined according to a chroma position rule that maps the chroma position information to phase information in an X dimension and phase information in a Y dimension, wherein the chroma position rule maps the chroma position information to phase information that include phase positions -0.5, -0.25, 0, 0.25, 0.5, 0.75, 1, 1.25 and 1.5, where the phase positions are in pixel units, wherein the decoding of the chroma position information comprises decoding a first syntax element that represents the phase information in the X dimension and a second syntax element that represents the phase information in the Y dimension; performing a rotation or flipping operation to the encoded digital image data while the still image is in the compressed domain, including performing the flipping operation by modifying transform coefficients in transform blocks generated using the reversible lapped transform or performing the rotation operation by modifying and transposing the transform coefficients in the transform blocks, wherein the modifying the transform coefficients comprises negating the sign of odd-symmetric transform coefficients in the transform blocks, and modifying the chroma position information to reflect the rotation or flipping operation; decoding the still image from the encoded digital image data using an inverse of a the reversible lapped transform; and outputting a decoded still image.