1, let's take a look at the original PSD file size of 89.2M, which is still relatively large for a poster.

2. Let's open our PSD file first and click File-Save as in the top menu bar.

3. In the Save As window, save the file as a TIFF format, and then click Save.

4. Then, in the TIFF option, select "LZW" for image compression, select "ZIP" for layer compression (slow storage speed and small file size), and then click "OK".

5. Select OK button directly in the pop-up prompt box, and save successfully.

6. We can view the file properties of the saved TIFF with the right mouse button, and we can see that the file size has been compressed to 37.4M.