PhotoGrav Software for the Laser - The Basics

There are four basic steps to engrave a photograph:

1. Scan the photo and save it on disk as a grayscale (8-bit) ".BMP" file.
2. Edit the file in CorelDRAW PhotoPaint or Adobe PhotoShop. Make sure the photo is the actual engraved size before sending out to PhotoGrav.
3. Process that file in PhotoGrav and save the "Engraved Image" as a file on disk.
4. Import that file into CorelDraw, or equivalent, and engrave it in the usual fashion.

There are some important rules to keep in mind in accomplishing the above four steps:

Step 1: Scan the Photo

• If you are using an Epilog or LMI laser engraver, then the image which is saved on disk just prior to PhotoGrav processing should have a dpi (dots per inch) of either 300 or 600. If the laser engraver is a ULS, the image dpi should be 250 or 500. Generally, 250 or 300 dpi is adequate resolution for the PhotoGrav input image.

Step 2: Scan the Photo

• The image should be the right size, in inches, for engraving before it is processed in PhotoGrav. You can use Adobe PhotoShop, Corel Photopaint, or some other appropriate image processing program to set the size and dpi of the image before storing it on disk, i.e., the photo can be scanned at some convenient size and resolution and then modified in one of these programs. Note: Editing can be done in CorelDRAW, but superior results are achieved in the Paint programs.
• The image to be processed by PhotoGrav must be a grayscale (8-bit) ".BMP" image file. If you are dealing with a color photo, then you can scan it in color if you wish and use one of the image processing programs to convert it to a grayscale (8-bit) image just before saving it on disk.

Step 3: Process the file in PhotoGraV

• Open the image in PhotoGrav. PhotoGrav will only open 8-bit grayscale images.
• Select the material on which you are going to engrave the photo. This can be done by clicking the" Select Material" button and then choosing a material from the resulting list or by clicking the "Load Params" button and selecting a named parameter set. There are a number of named parameter sets that are furnished on the sixth (extra) 3.5" diskette as described in one of the cover letters accompanying the PhotoGrav program. These parameter sets are equivalent to selecting a material but have improved parameters compared to the original materials. It is advisable to copy these parameter sets to a subdirectory on your hard disk and use them as described in the referenced cover letter.
• Click the "Auto Process" button. PhotoGraV processes the image and displays three images on the resulting screen although only one image is initially visible. You can view the three images in sequence by clicking the "Cycle Images" button on the toolbar in the upper part of the screen. The three images are:

1. The "Original Image": This is just the input image.
2. The "Simulation Image": This is an attempt to simulate what your engraving will look like.
3. The "Engraved Image": This is the binary image (black and white dots) that should be saved on your disk for subsequent import to Corel draw or equivalent.

Step 4. Import the "Engraved Image" file into CorelDRAW and engrave it.

• The image file that is imported into CorelDRAW should not be resized nor rotated once it is in Corel draw. You can, however, position the image file wherever you want on the page, flip the image file left-to-right or top-to-bottom, and add text anywhere on the page.
• The engraving resolution, i.e., that resolution or dpi that is specified in the Print driver, should be equal to the dpi of the imported image file or a factor of two larger. That is:

1. For Epilog and LMI engravers, you should usually engrave most woods at 300 dpi and most other materials at 600 dpi.
2. For ULS engravers, you should usually engrave most woods at 250 dpi and most other materials at 500 dpi.
   With practice and experience, you will find that you can often achieve almost identical results for some materials by engraving at the lower (250 or 300) resolution although you have to adjust the power and speed appropriately as specified in one of the "Rules of Thumb" occurring later in this Guide.

Note: do not resize the photo. If resizing is required, it must go back through PhotoGrav after it is resized.