Photo engraved on marble

[Lisabeth Shaffer]

I completed this engraving and realized that when I paused the machine and restarted it (in the same position) it left a very distinct line.

Has this happened to you?

I have a VL300 40watt.

Is there any way to "smooth" out the line so it isn't so obvious?

Thank you in advance.

Marble photo.jpg

[Dan Hintz]

First off, I would choose another dither pattern... the one you're using is meant for low-res print (e.g., newspaper). How long was the laser paused? There is a distinct increase in power on the bottom half of the image compared to the top, and the line is quite defined... makes me think the power was either inadvertently increased or the tube cooled down during the pause.

[Scott Woodson]

It almost appears as if the DPI increased from the top to the bottom. Looks like 300 DPI on top and 400/600 DPI on the bottom. Looks like more pixels in the lower half vice a power issue.

[Lisabeth Shaffer]

I have the dpi set at 600. I tried it at 300, but it was too pixelated.

I did pause the machine for a long time. Now I know. Thank you.

How would you change the dithering? I used ULS 1-touch to process the photo.

Thank you for your responses.

[Kev Williams]

I blew the picture up- the dithering appears (to me) to be the same. What's really odd is, the 2 trees on the left, from the extreme left side to halfway into the second tree, there's NO change whatsoever. All the change is from the center of the second tree-RIGHT>> ??

Check it out-- maybe the problem is the marble?

[Dan Hintz]

I have the dpi set at 600. I tried it at 300, but it was too pixelated.

300dpi is still a decent resolution... if you're seeing pixelation at 300, either you have a mismatch with your input-to-output dpi, or something serious is going on.

Check it out-- maybe the problem is the marble?

Nope. That's a very regular pattern, and marble itself doesn't cause that. That looks like a halftone screen.

[Mike Null]

With respect to the photo quality I wonder what the resolution of the photo is. If you just downloaded it from the internet then it won't matter what resolution you run it at.

[Lisabeth Shaffer]

300dpi is still a decent resolution... if you're seeing pixelation at 300, either you have a mismatch with your input-to-output dpi, or something serious is going on.

I changed from 300dpi to 600dpi because I engraved them side by side on a sample piece of marble and there is a distinct difference. How would I check that my input-to-output dpi matches?

This is a pretty poor picture, but you can still see the difference in the 300dpi on the left and the 600dpi on the right. Maybe my speed and power weren't set correctly.

[Dan Hintz]

With respect to the photo quality I wonder what the resolution of the photo is. If you just downloaded it from the internet then it won't matter what resolution you run it at.

Misworded, maybe? Plenty of high-res images on the net. You just don't want to pluck images straight off of webpages since they're usually <1k x 1k res.

I changed from 300dpi to 600dpi because I engraved them side by side on a sample piece of marble and there is a distinct difference. How would I check that my input-to-output dpi matches?

This is a pretty poor picture, but you can still see the difference in the 300dpi on the left and the 600dpi on the right. Maybe my speed and power weren't set correctly.

Your pic is way too blurry to make any sort of conclusion, but it looks like one is only a portion of the other (perhaps the "600dpi" one?). If your image is 300 dpi to start with, then lasering at some multiple of that (300, 600, 1200, etc.) will not lose you anything. Taking an image that's, for example, 280dpi and lasering at 300 will begin to show some odd artifacts. If you printed the first picture at 600dpi, it should not change the size of the image or what portion of the image is engraved, it should only engrave each pixel 4 times as often, but in the same space as the previous 1 pixel. I think you're comparing apples sitting in an orange basket.

[Chuck Stone]

I blew the picture up- the dithering appears (to me) to be the same. What's really odd is, the 2 trees on the left, from the extreme left side to halfway into the second tree, there's NO change whatsoever. All the change is from the center of the second tree-RIGHT>> ??

Kev, it might be your monitor. I can clearly see the difference in the two left trees. It isn't as obvious in
the darker areas only because those aren't engraved as much. But I can see the line continue through
the second tree and into the leftmost one.

[Lee DeRaud]

Nope. That's a very regular pattern, and marble itself doesn't cause that. That looks like a halftone screen.

She processed it with ULS 1-touch, which uses a really odd combination of half-tone and Jarvis (I think...whatever the one is called that uses the squiggly lines). I recall looking at it when it first came out and was distinctly underwhelmed with the results.

[Brian Robison]

Don't tell me that, I have it one the way, should be here tomorrow! LOL

[Bill Cunningham]

That looks more like granite than marble!! If it's marble it will turn whiter on a second pass and may cure the problem. If it's granite you can't do that.. If it's lasersketch 'marble' it's really a fine granite.. Real marble is just about goof proof.. High power, low speed two passes, the image only gets white and better.

[Mike Null]

Dan

You are correct.

With respect to the photo quality I wonder what the resolution of the photo is. If you just downloaded it from the internet then it won't matter what resolution you run it at.

I generalized assuming it might have been a 72 dpi download.