To ensure the best contrast in your photo engraving, start with a high-quality image that features clear details and distinct light and dark areas. Here are some steps to enhance contrast:

1. Adjust Brightness and Contrast: Use photo editing software to increase the contrast and optimize brightness. Aim for a balance that highlights important elements without losing detail.

2. Select the Right Image: Choose an image with strong tonal ranges. Portraits or images with varied textures often translate well into engravings.

3. Convert to Grayscale: Convert your image to grayscale to help visualize the contrast without color distractions. This will allow you to see how light and dark areas interact.

4. Test Engraving Settings: Before committing to the final piece, do test engravings at different settings. Adjust power and speed settings to achieve the desired depth while retaining clarity.

5. Optimize for the Material: Different materials respond uniquely to engraving, so tailor your approach to the specific substrate for optimal contrast.

By following these tips, you can ensure your photo engraving will have the best possible contrast, making it visually striking and detailed.