How to convert 4-dimensional TIFF image from RGB to Grayscale ?

I have taken an image from HP Laserjet Scanner 500 MFP M525 which contains six sub images(TIFF format and 300 dpi) . My aim is to get the gray-scale value for each of the sub image. To obtain the sub images from the main image, I made six copies of have of the original image and cropped them one by one to obtain the six images. After cropping the original image and reading the image, some images are 3 dimensional and rest are 4 dimensional. The problem is that matlab is unable to convert the 4 dimensional image from RGB to gray-scale. So, I am not able to fulfill my objective to get the gray-scale value. As a solution to this, I took images of JPEG format and they are process able but my requirement is minimum loss of information due to which TIFF image is the requirement of the hour. Also, attaching the zip file of original image with the six sub images and code for gray-scale value. Why some images are 3 dimensional and rest of the images are 4-dimensional?

[Walter Roberson]

Duplicates https://www.mathworks.com/matlabcentral/answers/337166-why-do-i-get-an-error-when-rgb-image-tiff-is-converted-to-grayscale-the-value-of-such-image-in

[KSSV]

Sumit Chaudhary , I have answered your question at the link given by Walter Roberson. It is not suggested to ask same question.

[Sumit Chaudhary]

okay. I will take care of it in the future.