Multiple colors - gradients? in Shape relief window

General MeshCAM Art Questions

Multiple colors - gradients? in Shape relief window

Postby sjj47 » Tue Aug 09, 2016 9:07 am

Hi - I've been importing some simple figures into MeshCAM in order to practice with the Relief Builder. My problem is that I keep getting multiple colors and gradients? from my png files. Here's an example I made in Inkscape. I made sure I selected Flat colors - no gradients AND set the stroke to no color AND turned off anti-aliasing.

inkscape.JPG
inkscape.JPG (14.39 KiB) Viewed 998 times


When I open it with MeshCAM > Relief > Shape Relief I get a lot more than 3 colors:

mc1.JPG
mc1.JPG (33.8 KiB) Viewed 998 times


And when I select the three colors and use Flat, 0.1", I get this:

mc2.JPG
mc2.JPG (23.86 KiB) Viewed 998 times


Which looks to me like what appears to be a flat color actually includes some gradients.

Obviously this is not the effect I'm going for. Any idea how I can fix this?

Thanks!
Steve - Shapeoko 3; Inkscape, MakerCAM, UGS, bCNC.
Software engineer professional; woodworker journeyman; CNC tyro;
sjj47
 
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Re: Multiple colors - gradients? in Shape relief window

Postby Randy » Thu Aug 11, 2016 10:34 pm

Steve, if your first embedded image is your actual MeshCAM input file, it's a JPEG. Your last heightmap screenshot also shows typical JPEG compression artifacts. Make sure you are actually saving in PNG format, which is lossless, as I'm sure you expect.

Randy
All opinions in this post are mine alone. I am not a MeshCAM employee, I do not have a financial interest in MeshCAM, nor do I speak for MeshCAM. MeshCAM user since Beta 5 in 2003. viewtopic.php?f=11&t=15333 :ugeek:
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Re: Multiple colors - gradients? in Shape relief window

Postby AdPrinter » Wed Aug 17, 2016 8:59 am

In the "Tutorial" reply post, I mentioned that the Color Management of Corel DRAW is excellent for working with colors, and MC Art. I also mentioned, that a Book could be written on the subject alone! But to offer my experience with MC Art, and importing files which came in with these "Gradients" it all comes down to the color management settings of the software you are using to create your artwork. RGB is the color format MeshCAM Art likes. And PNG is the file format it likes. If your bitmap editor software has a setting such as "Optimize for the Web", then USE IT! Web pages also like the RGB color format. As I said, the subject could literally fill a book! You need to become familiar with terms such as ICC, which is an acronym for "International Color Consortium". A group of folks, who attempt to develop standards for color information embedded into computer files, so that the color one sees on a monitor on this side of the world, is the same color one would see on a monitor on the other side of the world. Or the colors one sees on a monitor, will be printed in that specific color on a digital printer. Or the color is intended to be printed on an offset printing press, the rules changes for it all! If the color is source color, as opposed to reflective color, the rules are also different. The more one learns about color management, the more one comes to the realization that it is a VERY COMPLEX SUBJECT! I have the unique perspective, as a retired printer. So I do have perhaps a "little" better comprehension of the different purposes of color management, than the average Joe. But even I am limited in my own comprehension, as it pertains to MeshCAM Art. Because I have spent many sleepless nights, wrestling with different color settings of Corel DRAW, in an effort to get my artwork down to a simple 4 colors for importing into MeshCAM Art. Only to discover (FINALLY) that it was NOT the color settings at all, but rather the resolution I was exporting the image as! I changed the default resolution to 500 pixels per inch (for exporting FROM Corel DRAW), and change it 115 pixels per inch, when opening into MeshCAM Art. This works to provide the greatest detail of most of the artwork that I work with. Hope this helps you. I paid dearly for this information, at the school of hard knocks!
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Re: Multiple colors Shape relief window - sort of solved

Postby sjj47 » Mon Aug 22, 2016 3:50 am

AdPrinter -- thanks for your response! I will try your suggestion regarding the ppi settings -- I think I read somewhere else on the forum that colors in the palette multiplied or diminished depending on the pixel density selected -- which just seems bizarre.

In the meantime I'd thought I'd describe the method I eventually worked out, in case it helps someone else. I used Inkscape to create the vector drawing and then Gimp (both free) to create the PNG file that is opened by MeshCAM.

    In Inkscape, turn Antialiasing OFF
    Select a reduced color palette (I defined a palette of 16 RGB colors and called it "MeshCAM_reduced")
    Create the drawing, filling each Object with one of the colors from the palette
    Verify that each color has NO outline (0.00 pixel stroke) and NO gradients ("Flat").
    Inkscape > File > Export PNG Image ... > filename

    Gimp > Open > filename
    Colors > Posterize > 3 (I used "3" even though I had a dozen colors in the image. More than 3 causes problems)
    File > Export > filename2.png

    MeshCAM > File > Open > filename2.png

I still get 3-4 extra colors in the Shape relief palette, but whatever artifacts they cause don't seem to have much affect on the finished product.

No doubt someone with more knowledge could come up with a better process. I just needed something I could use, so I applied my usual crude try-everything-until-something-sort-of-works approach.

In any event, I'm pretty happy with the results.

Incidentally, I think MeshCAM Art is capable of a lot more than making medallions -- :)

First draft -

mc1.JPG
mc1.JPG (25.3 KiB) Viewed 958 times


Final version - Milled lid of box:

Ted_box_lid2.jpg
Ted_box_lid2.jpg (143.88 KiB) Viewed 958 times
Steve - Shapeoko 3; Inkscape, MakerCAM, UGS, bCNC.
Software engineer professional; woodworker journeyman; CNC tyro;
sjj47
 
Posts: 11
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Re: Multiple colors - gradients? in Shape relief window

Postby AdPrinter » Sat Sep 10, 2016 8:47 am

Steve,
Looks like you're getting the hang of it. One tip (to reduce the "dimple" in the sun ray behind the bicycle seat) when you are using the Shape Editor, select BOTH the color of the bicycle seat, and the sun ray, before entering the Shape info. This will cause MC to treat both colors as a single color, and shape them together. Then, go back into the shape editor, and select ONLY the color of the bicycle seat. Then enter the info to shape it individually as desired (just make sure that the Start Dept you enter is slightly higher than the start depth you entered on the sun ray). Keep at it, you'll do fine!
Have a Blessed Day!
-Michael
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