View Full Version : Photo engraving

Robert E Miller
12-16-2010, 10:37 PM
I am new to lasers but not to cnc machining. I am ordering a rabitt 60w in a few days to add to my capabilities. I have been searching the web for any and all pointers these last 3 weeks. My first easy question is, when doing photo engraving is it best to have a high resolution picture from say a digital camera? I understand it's important to have a good clean picture but what can you get away with? I have read people scanning pictures too.
I am getting photograv and corel draw x5 so I will have a ton to learn.

Bill Cunningham
12-16-2010, 11:17 PM
The usual minimum res I will accept is 2000 pixels on the long end.. I usually explain this in great detail to my customer, then they send me a 400 x 600 pixel image.:mad:.. Most customers really don't have a clue.. They set their digital cameras to the highest number of photos they can fit on the chip, and because it looks great on screen it must be fine for everything... It really all boils down to the size of photograph the customer wants engraved, and what they want it engraved into.. Glass only needs 150ppi so the 600 pixel image will give you a decent image up to 4 inches across, into 'real' marble 600 ppi will give you an image 2" across.. As for how the Chinese lasers deal with photographs? I have no idea... In most cases you can do a bit of bit stretching, I have gotten good results from poor res photos, if their in focus.. Photograv seems to sharpen those images up a bit particularly when preparing for granite engraving..

Ahh I see this was your first post!! Welcome to the creek

Larry Bratton
12-17-2010, 10:58 AM
You are delving into one of the most confusing aspects of laser engraving. To answer your first easy question..YES, the higher the resolution the better. You can always size it to whatever you need, not true with low res photos. You will encounter the abbreviations DPI and PPI, these are sometimes used interchangeably in error. DPI (DOTS PER INCH) is a printer term that describes a printers (laser's) cabability. PPI (PIXELS PER INCH) is relevant to screen resolution for computers, tvs etc. But, like I said, you can get confused real easy, for example, Photoshop refers to an image as having XXX PPI at the size menu, whereas Corel Photopaint will refer to the same thing as DPI. Generally, a good rule of thumb is to acquire images at 300 DPI or higher. My Epilog is capable of producing 1200 dpi, that would mean it is going to put down 1200 dots vertically as well as 1200 dots horizontally in a 1" square.

If your getting Photograv, it likes images of 300dpi. If you import an image into Photograv that is less than 300, I believe it returns an error message. In general, images that are downloaded from the internet, are typically 72 dpi and will give less than desirable results. I have, in some cases, used very large,in focus jpgs (like 18"w x whatever length) at 72dpi, size them down to say 5x7 and get pretty good results. In this case, you would need to size them down in Corel Photopaint and reset the resolution to 300 dpi to avoid getting that error message. Be advised though, if you do a bit of research and study, you can accomplish some very satisfactory results using Corel only and save that $300 or so your about to spend on Photograv. (been there, done that).

Welcome to Sawmill Creek!