  Quantum image processing is an emerging topic in the field of quantum
information and technology. In this paper, we propose a new quantum image
representation of RGB images, which is an improvement to all the existing
representations in terms of using minimum resource. We use two entangled
quantum registers constituting of total 7 qutrits to encode the color channels
and their intensities. Additionally, we generalize the existing encoding
methods by using both qubits and qutrits to encode the pixel positions of a
rectangular image. This hybrid-qudit approach aligns well with the current
progress of NISQ devices in incorporating higher dimensional quantum systems
than qubits. We then describe the image encoding method using higher-order
qubit-qutrit gates, and demonstrate the decomposition of these gates in terms
of simpler elementary gates. We use the Google Cirq's quantum simulator to
verify the image retrieval. We show that the complexity of the image encoding
process is linear in the number of pixels. Lastly, we discuss the image
compression and some basic RGB image processing protocols using our
representation.
