A couple of questions re: the Gold Method

[Jamie Bell]

Hello to all! I have been engraving since '06 on my Epilog 75W helix, and still don't get the best results on photos. Tried EVERY thing. I see what others are doing on the web, and just cannot touch it. A few have been pretty good, but not what I call great, esp. considering all the years I have been trying. So, I have decided to start over. I looked up and read about the Gold Method, but don't have PhotoShop, and cannot afford it right now. I use PhotoGrav and Corel X3 (I do have PhotoPaint, too). My question is on the following instructions (see below), I get lost after #4 ?? And when I try to convert the results from steps 1 to 4 in PhotoPaint, I take that image back to Corel Draw and try to convert it to a half-tone using Jarvis or one of the diffusion modes (cannot see how to do this in PhotoPaint), but it seems the image is very poor after that. What should I do or how do I do this? I primarily engrave photos on alder, maple or super black granite from LaserSketch. I should also mention that my laser tube is probably on it's last leg, and the last time I had it tested a few months ago, it was only putting out 40 W. Yikes! Cannot afford that either! ;)

I also wonder about using Corel's "Mask" feature to adjust certain parts of an image for better engraving, such as when the face is too dark ?? I just cannot figure it out? Any suggestions?
Thanks so much for being here and all your help! Jamie

1) Convert to 8 bit greyscale (image/mode/greyscale)
2) Resize the image to the size its gonna get engraved using 150-300 ppi (150 for less detail)
(image/image size)
3) Bump up contrast and brightness about +25 in
both cases - you dont want the pic to be insipid areas of medium grey. (image/adjusyments/brightess-contrast)
4) Heres the VITAL part - use unsharp mask at 500% and a radius of 3-5 pixels - threshold 0 - this will exaggerate edges radically , but thats what you need. In fact you can do this and then STILL add another unsharp mask at 150 % , 1pixel and 0 threshold AFTER the 1st unsharp if you want even more edge detection
(filter/sharpuen/unsharp mask)
5) Convert to a bitmap using 125-150ppi and a diffusion pattern. (image/mode/bitmap)
5) laser.

[Larry Bratton]

Jamie:
Start off with the image in Corel Draw. Then Edit Bitmap. It will open in Photopaint. Do the steps as you understand them. Then, as far as Step 5 goes, go to Image/Convert to 1bit. When that opens, under Conversion Method choose one of the patterns. I like Floyd Steinburg but Jarvis or Stuki will work too. Then, just close PP and it will ask if you want to save. Say Yes and it will make the changes and save your result to Corel Draw. Photopaint is a little different from Photoshop in this step.

Also Jamie, fundamental to getting a good result is to start with a good photo. It needs to be 200-300dpi to begin with, not rezzed up to that with the software.

[Jamie Bell]

Larry: Thank you. That helps alot. When you say 200-300 to start with what do you mean? Let's say a customer brings me a photo to scan. just your typical 4x6 print. I scan that at 300 and engrave it at 300, is that what you mean?

[Larry Bratton]

Jamie:
Exactly. Many people try and use content that is downloaded off the internet. Typically, although the images appear great on screen, they are of low quality for our engraving purposes. Usually those images will be in the 72 - 96 dpi range. The better the original photo the better your engraving result will be.

[Jamie Bell]

I cannot wait to get to the office tomorrow and give this a try!! I cannot believe I was doing everything wrong all this time! I was re-sizing the image by pulling the corners, instead of using the resize function. I never realized that I should also check the dpi on this screen, too. And the kicker is the unmasking tool. Will post results tomorrow! I am so excited!!!

[Jamie Bell]

One more thing, is anyone else out there using a 75W Helix? What settings do you use for photos in wood and granite/marble? I either get too washed out, or too burned in.

[Martin Boekers]

If your tube is going, our settings won't be close!

On photos esp granite less power is better.
Use some scraps and set the outer perameters, one to much burned and one not enough.
Then split the difference half way, keep doing this and you get there quicker than creeping up on it.

Some have used a grey scale chart (you can google one) and use that for a bench mark test.
Sounds like it has potential, just haven't worked with it yet.

Marble is MUCH more forgiving than granite.

Marty

[Larry Bratton]

Jamie:
You should use the Re-Sample tool in Photopaint. When you open your bitmap image with that, it will show you what dpi it is and the actual size of it. The tool is Unsharp Mask under the Effects drop down -Sharpen. If I'm not mistaken though, I think Rodne's (Gold) method is aimed at prep for granite or marble. You can experiment with it though. Remember if your doing a photo on black granite or marble (or black acrylic for that matter), after you get everything else done it has to be Inverted.(Image/Transform/Invert) After you get the image into Corel Draw and ready to send to the laser, don't re size it or anything. Place it where you want it and send it to the laser. Since it is already dithered, just use Standard as the dithering method, it doesn't have any effect now. Watch this video http://www.youtube.com/watch?v=ZubRDUrg_7k

[Jamie Bell]

Thanks Marty. I will google that. I find that even with the tube going, if I just bump up the power 5-10 more, then I get about the same as I always have. However, admit it's getting dicey. Just for S's and G's, what settings are you using? Thanks, again.

[Martin Boekers]

The granite never worked well with me on photos, vector art or text was ok.

On wood the last one I did I believe was 100 speed 60 power not sure offhand, I typically do a small test on scrap first.
There was a BIG difference in just a 5 point move.

[Jamie Bell]

Larry, Right! I think I got it now. I plan on playing around all day tomorrow. (check out the photos tomorrow of my results!) So, I cannot use the Gold method on wood? What should I do differnt there? Thanks for the link!

Marty: That is what I had been using on wood, also. I know, 5 up can be a lot. Thank Goodness for scrap materials.

[Rodne Gold]

Works on wood.. :)

[Larry Bratton]

You can use it on wood..Mr Gold says so in the above post :) Best to just experiment with different things until you find what works best for your machine.

[Jamie Bell]

Thank you, Mr. Gold!

[Bill Cunningham]

Also keep one thing in mind Jamie.. When you import a ready to engrave 1 bit piece of dithered artwork into Corel, it's going to look BAD (with a capitol 'B':D) A computer screen does not like raw 1 bit images, so they look rather strange, and nothing like what you would expect a good photo to look like. Ignore what it looks like, and engrave it.. Your computer won't like it, but your laser will...

[Larry Bratton]

to elaborate a bit on Bills post...Corel doesn't render 1 bit files very well. You can get a better representation of what it actually looks like if you Save it to PDF and view it with Acrobat. I also look at the 1 bit files very carefully, zoomed in, for anything that I may not want to be there. Remember, black pixels fire the laser and white ones don't. Sometimes you may want to adjust something. Just Edit Bitmap again, erase any weird stuff and save it back to Corel if you didn't see it prior.

[Jamie Bell]

Larry and Bill: Thanks again. I did find that my 1-bits looked terrible, too, and really wondered if or how it would engrave. I wonder about the faces the most. Since they are all covered in black dot pixels ?? But, you don't want any major "white" areas either, right? Esp. when engraving on wood?

[Larry Bratton]

Like Bill said..don't worry about what those look like. Engrave them and see what you get. The black pixels make the laser fire.