The image is too small to cover your panel at its pixel to inch size so here is what I did.
1) I rotated the image 90 degrees so I could think about the process with X being the length and Y being the height. This is not necessary as you can rotate the image via the STLayout settings, but it easier to think out logically if you do.
2. I did a pixel to inch calculation using 96dpi (here is a calculator: https://www.ninjaunits.com/converters/pixels/pixels-inches/
3. First attached image shows the X (S) and Y (T) image size in inches with no offset.
4. Second image shows the S and T scale at twice the original size and the S & T offset set to half (or the original size in this case).
5. Third image shows the result. If the scale of the grain on the panel is too big, you need to tweak the scale, by experimenting as shown in the tip keeping in mind that S cale may not translate well, while the T scale may be fine based on the image grain itself, with the timber butt together lines.
6. Note that seamless images work best, but they are not as plentiful as one would like.
EDIT: you can find the image pixel size by hovering your cursor over it. May need to select it first. See last image.