Techniques are described for efficient high-resolution output of an image captured using a high-pixel-count image sensor based on pixel binning followed by luminance-guided umsampling. For example, an image sensor array is configured according to a red-green-blue-luminance (RGBL) CFA pattern, such that at least 50-percent of the imaging pixels of the array are luminance (L) pixels. Pixel binning is used during readout of the array to concurrently generate a downsampled RGB capture frame and a downsampled L capture frame. Following the readout, the L capture frame is upsampled (e.g., by upscaling and interpolation) to generate an L guide frame with 100-percent luminance density. An upsampled RGB frame can then be generated by interpolating the RGB capture frame based both on known neighboring RGB information (e.g., from the RGB capture frame and previously interpolated information), as adjusted based on local luminance information from the L guide frame.