RGB Bitmap Laser

[Peter Meacham]

I am trying to raster engrave a RGB bitmap of an old covered wagon but need to change all the colors to black to proceed. Can anyone advise how to change the bitmap to black please (or advise how I should engrave the bitmap as is). Using Corel Draw 12. Thanks, Pete

[Darren Null]

Using what you've got:

1) resize the image to the size you want to burn it at

2) Click on "bitmap-->convert to bitmap". You'll want 300 or 150-200dpi depending on the material you're burning on.

3) Then "bitmap-->mode-->convert to black and white"
In the convert to black and white, there's a drop down box where you can select the conversion method. My favourite is the Floyd-Steinberg

And burn it.

For this sort of operation, most folks here use a program called Photograv that is specifically for converting images to a burnable form.
I personally use a photoshop plugin called andromeda etchtone because it's a quarter of the price for comparable results and I'm a tightwad. Also, I like photoshop.

[Vicky Orsini]

You should be able to engrave in colour, or convert to greyscale if you're so inclined. Converting to pure black & white, you might lose some detail. To convert to greyscale, go to the menus at the top of the page. You have one called Bitmaps. Click on that, and you'll get a bunch of option opened up underneath it. One of them is Mode. This is where you change it to greyscale or B&W if you so desire.

Hope this helps!

[Joe Pelonio]

Select the object, then click at top on Bitmaps, Mode, B&W.

[Vicky Orsini]

Aw, Darren, you're a quicker typist than I am! :D

[Darren Null]

Me typing is quick but me thinkin' is slow to make up for it.

[Pete Meacham]

Thanks everyone. Well, I don't have a dropdown menu for any conversion method and the B/W change loses too much detail. The Grayscale looks real good but I don't know if it will engrave (using black as the engraving color) - I will try. Pete

[Darren Null]

Bitmap-->mode-->convert to black and white.

A box labelled 'convert to 1-bit' comes up with various options including conversion method (could be algorhythm in v12, but there should be SOMETHING there...). I'm on V13, but I can't believe that they're that different.

Greyscale will work, but pretty well only on wood or suede where you can burn at various strengths for different amounts of charring...for most materials you either burn a hole or you don't, so it's 1-bit you need.

Also, don't be misled by what you see on the screen in CorelDraw. A properly-rendered image (photograv or etchtone or other method) looks absolutely awful on screen but burns considerably better than something that looks good on screen. Only experience will help you here, I'm afraid, or seeing different burns by different techniques on the same material side by side.

If it's an image that you need to get out and can't spend the time experimenting, I can etchtone it for you if you tell me what size you want it and what you're burning on. darren@laser-etching.com

[Pete Meacham]

Thanks Darren, I have emailed the file to you if you can assist please. Pete

[Richard Rumancik]

Thanks everyone. Well, I don't have a dropdown menu for any conversion method and the B/W change loses too much detail. The Grayscale looks real good but I don't know if it will engrave (using black as the engraving color) - I will try. Pete

Pete, if you can't edit the bitmap while in CorelDraw, you might have to save the greyscale image from CorelDraw and open it up in Photopaint separately.

eg From CorelDraw, select the greyscale bitmap you created-> export selected -> select tif export, give it a file name etc, and answer all questions carefully. Write it down so you don't forget what you did. Then open the file in Photopaint, go to Image ->color mode -> b/w -> select conversion (Jarvis, Stuki, Floyd, etc). I like Stuki myself. Then play with the slider for intensity (you will need to experiment.) As was noted, it will not necessarily look good to the eye. You will get a feel for what will laser properly. Again, write down what values you used. Save the tif result with a new name. Import back into CorelDraw for placement. If you don't like the lasered image, go back to Paint and try again with adjusted parameters.

Engraving using the greyscale and letting the laser convert is hit and miss. Converting yourself gives you much more control of the process.

[Darren Null]

Pete- what size is the end product?

[Pete Meacham]

Darren - it should be the rectangular box around the artwork - I think it is 12 x 8 Inches. The actual bitmap artwork that I am trying to color black is 8 wide by 6.224 tall.

Thanks, Pete

[Pete Meacham]

Richard - sorry, I did not see your reply earlier. I will also see what Darren is able to figure out. Thanks. Pete

[Bill Cunningham]

When you just do a mode convert to black and white, you can adjust the 'threshold' up and down to add or remove detail.. Trace is also good for this, use trace to convert to black and white, adjust the threshhold, and trace to curves.. You now hav a vector file that you can make any size.. OR, simply upload to the stanford vector magic site, and have their tracer do it for you.. it works GREAT!!

http://vectormagic.stanford.edu/

[Peter Meacham]

Bill, Joe, Vicky, Darren and Richard

Thanks much for all your inputs - I ended up using Richard's method and it came out great. It looks like Bill's suggestions would work very well. I think I will try the Stanford Vectormagic for my next conversion. Thanks again all, great support.

[Darren Null]

Hi Peter- sorry I didn't do your graphic...my connection died (with an advert due to come out in the paper the next day and my site half-completed!).

The wagon in the graphic was a bit over-expanded so while I would normally use etchtone; in this case I had expanded it a bit and was halfway through sending it to VectorMagic when everything died.
Vectormagic would have bought back a lot of clarity; then it would just have been a matter of changing the various greys to black for a high-quality lasering image...being pure (or 80%) black (personal preference) I would just have left the image as a vector and gone for it.

[Peter Meacham]

Darren - sorry your computer had problems - you know they say that computers have a stress detector built in, so they can fail when you need them the most. I had not heard of Etchtone so I just went and looked it up, looks interesting and I will have to explore it more.
Anyway, I am OK now and I hope that you are as well. Thanks for the effort. Pete

[Darren Null]

If mine had a stress detector in it would have exploded; taking out several kilometers around me.

I favour etchtone over photograv myself...but that could just be because I'm used to working in photoshop. Just adjust the image to the size you want and the dpi to the material you're working with and press the 'do it' button. Results aren't quite as good as photograv (2.11- not tried 3.0 yet) but there's a lot less messing about and it's a quarter of the price. If you're not happy in photoshop, probably photograv is the better option...different strokes etc.