if all three jpeg files are the same resolution it will be easy simply
create a new image large enough to hold all three images and at the same
resolution. Select the "move" toolbar button and move each image on to the
new b lank image. If the three images are at different resolutions, then
create a blank file at the largest resolution of the three. Move the images
as before. After you complete the move, each image will be on a seperate
layer. If you need to to enlarge or reduce any image, select the layer it's
on and select Edit -> Transform-> scale. hold the shift key down( to keep
proportions) and shrink or enlarge as needed. press <enter> when completed.
flatten the image and save as Tiff. That's all!
I think tiff generator programmes can enable to quickly create files. i have usetiff generator which batch generate tiff files in a short time.If you wanna save these complicated steps and find a easy way, you can google image generator and you will find many useful tools, or google how to batch generate tiff files to get instructive articles. if you haven´t found a good tool, you can have a try.