Thanks for inquiring Aspose.Imaging.
I have observed your requirements and like to share that even if a 32 or 24 bit image internally can have RGB distribution to make an image a gray scaled. So, in order to verify the image to be a gray scaled, you need to traverse every image pixel and verify if that is gray scaled or not.
Similarly, in order to check a blank image, you need to traverse every pixel and compare the two consecutive pixels. If there is any difference between two consecutive pixels, we cannot call image to be blank. Attach please find the sample code and sample images for verifying gray scale and blank images. I hope the shared information will be helpful.