I don't think there is a command that does this.
You could put the image in a memblock, and check the color of a pixel in the memblock.
From the help for CreateMemblockFromImage()
CreateMemblockFromImage
Description
Creates a memblock from a loaded image, atlas sub images are not supported. The image must exist and is unaffected by this command. The first 4 bytes of the memlbock store the image width, the next 4 bytes store the image height, the next 4 bytes store the bit depth, currently this will always be 32. After that the raw image data begins in the format RGBA, with each component stored in a single byte, so each pixel takes up 4 bytes. The size of the image data can be calculated by width*height*4 bytes (for now bit depth can be assumed to be 32 bits = 4 bytes). Note that due to little endian format reading the image data with bytes will return offsets 0=R, 1=G, 2=B, 3=A, but reading them all as a single integer will produce a value with A as the most significant byte, followed by B, then G, then R as the least significant byte. The pixel data starts in the top left corner of the image an proceeds left to right then top to bottom resulting in the image being stored as a sequence of rows ending in the bottom right corner. Returns an ID that can be used to reference this memblock in other commands.
You could calculate which pixel to check, or an easier way might be to just grab a 1x1 image of the pixel you need to check. That would give the color as the last 4 bytes of the memblock.
