This work examines the spectrum preserving properties of a multi-resolution analysis-based intensity modulation (MRAIM) when used for increasing the spatial resolution of spectral color images. The MRAIM algorithm is originally designed to fuse high-resolution panchromatic images with low-resolution spectral images in order to get high-resolution spectral images for remote sensing applications. Instead of panchromatic images, for which the MRAIM algorithm has originally been designed for, the MRAIM algorithm is implemented to use information from both grayscale and RGB color images. In order to utilize the information of the three channels included in RGB images, two different models are derived and examined. In addition, two kind of scaling factors are used for compensating possible differences between the images acquired at different resolution levels. The resulting high resolution spectral images are compared to the real acquired high resolution spectral images with respect to both maximum and average RMS errors and ΔE*_ab color differences under CIE illuminants D₆₅, A, F8 and F11. The used images are acquired by NuanceFX spectral imaging system, which allows the measuring of both spectral and RGB images at different resolution levels at identical geometry.