To compress large TIFF files in Adobe Photoshop without losing quality, follow these steps: Open the TIFF file in Photoshop, go to "Image" and select "Image Size," then change the resolution to 300 pixels/inch or lower. Next, select "File" and "Save As" to save the compressed file. Choose "TIFF" as the file format, and select "LZW Compression" from the compression dropdown. Finally, click "Save" to compress the file while maintaining its quality.