CHANGING SOLID COLORS IN A LOGO INTO SPECIFIED SHADES OF GRAY USING GIMP.

so based on that, and regardless of the machine can someone tell me how to identify the color used in each part and then turn that color into a particular pattern of dots where I assign values for both resolution (dot size) and dot density (how "dark" or "black" a color will become)?

Johnny5

MY SOLUTION (works for my image, see attached 8kb pdf or 18kb inkscape svg image):

1.) in gimp 2.8.22 use Filters -> Edge Detection:  algorithm set to Laplace

2.) (activate toolbox) Tools -> New Toolbox

Select the Pouring Paint Bucket (fill tool) from that toolbox

Next steps involve selecting a color and then applying it, this was done as follows:

3.) (open the color selector)  Windows → Dockable Dialogs → Colors:  in this window in the lower right is an empty field, if you click on the color pallet shown (might have to enlarge the window by dragging a corner) that empty field will be replaced by a hex value which represents the color you will be filling with when you sue the paint bucket.

4.) Open a website that converts given grey levels into hex code
https://rgb.to/

then I decided to make the top section at 20% darkness. 0,0,0 is black and 255,255,255 is white. Having 8 places to assign varying shades to I limit my range to 80% total (so the top is not blank white and is visible). The new range is 0-204 (80% times 255). Dividing by 7 gives about 30 per jump.

Enter 0,0,0 on the website I linked and copy the HEX code, then paste that code in the gimp color picker field referenced here previously; finally click the fill bucket in the bottom (solid black) outlined part.

enter 30,30,30 at the website, copy the hex value over to gimp color picker, then use the bucket on the next one.

5.) (not specified in initial conditions and requirements, outlining the individual shapes) Select-> ByColor : then select (holding shift to maintain previous selections after the first one) each of the pieces as they are still each a solid color (shade of gray)

6.) Select -> Grow: new dialog pops up and I choose the thickness of the line I want around each piece

7.) Make a new Layer, set it behind the one with the object, and ensure that it is selected (not the image part just working on) (this is strange, everyone had dialog boxes open that I did not so I had to google, too much information for my particular situation: if you have similar problems google 'how to access the BLAH BLAH", applies to all guides I suppose)

8.) using the color black and the bucket tool again, click on one of those shapes and the 'background' will fill with black, leaving the grown edges exposed.

9.) return to first layer with pieces and using shift select all pieces and activate the newsprint feature

10.) Filters -> Distorts -> Newsprint: this brings up a new dialog box, Many things to decide here but it's the last step aside from saving your file : )

I change the colors all to zero, I only want black. Choose Spot Function, I choose round for this. Under Resolution adjust the sliders to control the resolution and size of shapes and... whatever the hell "input SPI" means : )

Thanks again for the assistance, doubt this will help anyone else but I figured I should put my solution in since I do have the topic up.

I have an image that has separate distinct colors. (I think) they are solid colors and have pure blank or white between them. I "think" I have attached this image to this post........

I wish to engrave this image on a laser for my school.  My desired result is any of a number of options. I can be happy with greyscale, I can be quite happy with a 1 bit black and white dot pattern.

I prefer to keep the image of ideal quality (inkscape or I think perhaps pdf can do this?)  I have inkscape version 0.92.4 (5da689c313, 2019-01-14) installed, I used the default automatic exe installer.

I think I must perhaps somehow manually assign dot densities (or greyscale gradients) to the colors.

I have tried the following commands based on people who wanted to do things that sounded similar but didn't address my needs  or to piece various approaches together.

I have tried .extensions -> color -> black and white (no dot densities here just straight conversion to black or white based on luminosity threshold you can set.

I have tried extensions -> color -> greyscale (I do get various shades of grey but they are not ordered or graded properly, I need progressively higher densities of dots from top to bottom, each color clearly defined and darker than the one before while lighter than the one after. It gets neither of these things correct.

I have tried something I forgot the steps to but that allows me to convert to black and white by arranging a number of sliders (one 3 point slider and another 2 point slider), this noly converts each color to solid black or not (I later used this tool to clean up the edges of some other images that were black and white and remove edge noise, it's no good for this though.

I tried some other stuff but I don't remember because it was completely nothing to do with what I intended.

I also tried various methods to 'find edges' and set them but it gets a little messy at those edges and I'm hoping I can do better than that with an svg to work with.

Thanks everyone,

Johnny_5

Depends a bit on the laser system. Some will easily assign laser power-levels to greyscale values, with little user involvement.

Got a link or screenshot of the make and model of the laser?

sure it's the glowforge plus ( https://glowforge.com/our-products ).  It will do this with greyscale, however it then 'guesses' it does a decent job and will turn this into the dot pattern I want (I want to control dot density deff NOT cut depth, I'll sand after I'm done some : )  If I can assign my own dot densities I'll do that and if not I think I will (likely) be quite happy with what the glowforge software does with greyscale.

I will probably engrave at 450 lines per inch and (I think?, hell i'm new to all of this lol) I'll be happy with a dot resolution of no more than50 to 100 dots (lines) per inch? 

so based on that, and regardless of the machine can someone tell me how to identify the color used in each part and then turn that color into a particular pattern of dots where I assign values for both resolution (dot size) and dot density (how "dark" or "black" a color will become)?

Johnny5

I'd try using the Trace feature of the tile clones operations. It has color and size options.

http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Tiles-Trace.html

Another option is to make the different color areas independent objects, then assign a dot-pattern fill to each and adjust the size/spacing of the pattern fills.

cool, i'll google "making different colors/color areas into independent objects" and then on assigning Dot fill patterns. I suspect that edge recognition thing might come into play : )  Thanks!

This method starts with GIMP, then Inkscape.

https://youtu.be/QHaPLOyQbeo

can anyone get me pointed in doing this : "making different colors/color areas into independent objects", I really am not finding anything that's actually this (a lot of stuff kinda similar but not adaptable to this)

well I can't delete the previous post so... Thanks understood I'll do that. Didn't show for some reason when I refreshed.

ok i've learned a lot and I like that I can reasonably well stipple (or make into 'half-tone' I think it's called?) images now, however my current image and problem are still not quite solved yet.  I am not sure how to "make different colors or color areas into independent objects", once I do that I can decide how dark to make them (and learn how to do that too but I bet that is simple as hell), then I can do the steps re gimp and then inkscape.  Unfortunately when I do this with my current image I can only use luminosity or similar and I get dark places and light places out of order. I've searched on google but I don't find anything like this (or if so it is described in a different manner that I'm not guessing right in my search terms : )

If you have a pointer or link or a "different name for the process" please tell me, I'm kinda stuck and trying to do the edge detection thing and maybe create new shapes somehow once I have detected edges.

I'm really surprised I can't just click a color, then assign it to a greyscale value.  I have both gimp and inkscape so I'll keep looking and trying and checking back here for advice  : )

If I make the edge detection and proceed from there successfully I'll say how I did that back in my first post, i'm making progress and thanks for all the help so far : )

Johnny_5

I "think" I have attached this image to this post........

It seems your file did not get attached. You can try again to attach it to a reply or upload it to a sharing site and provide a link.

oh wow, thanks : ) it's an 18kb inkscape format svg lol, dunno why. It's an 8kb pdf now

Well, it's a bit fiddly, but this is the kind of result you might expect from trace clones.

wow, that's sweet. I saw some things that showed (I think) how to do the last and third from last : )

I should have included what I finished with I suppose?

the gimp file is 1.3 mg but the png is 8.5 mb.

see attached

having trouble attaching in an edit, see attached:

In the third image you ASSIGNED COLORS. Can you tell me what your method was to go about this, I see you listed Percentages, I feel there may be a much more easy way then using alternate websites like I mentioned in my adjusted first post @TylerDurden

I was just using the palette to assign colors. They might need adjusting depending on following operations.

I see, that's cool. And the % darkness is simply the actual name of the shade. Very nice, understood. Also, your demonstration is incredibly clear.

Another mostly legit method.    Cheat.

dude, that's really awesome. Thanks : )  I need to keep each piece distinct and not gradual like you showed but that's friggin good stuff, I'll be using that for other things : )

man I love learning

This is all one image but some colors are duplicated on different parts. I need to assign different shades of grey to everything (even the word RISE and the dark blue color at the bottom, same color but need to become different.  As previously stated, I would simply 'select by color', but that is not possible now. I have outlined the image by 5 pixels (I selected the hashmarks and then inverted selection, thereby selecting all parts of the image). I made layer then used the bucket tool to create a visible outline in black. Perhaps there is a way to use the outline to select and color certain letters and pieces of the globe.

  attached are both files

Thanks,

Johnny_5

Those uploads are jacked.

perhaps this will work

I'm just winging it here, but this is how I'd apply a stroke to the objects and assign fill colors to each. This is using the original svg from post #1.

Ungroup completely, add strokes to all and assign fills. 

(My screen-notation was in the way of the lower colors)

If "halftone dots" are needed, I'd apply the strokes after grayscale trace operations.

I can bring up the Windows -> Docable Dialogs -> colors (or colormap as well), but I don't get the colors along the bottom like you do. I've been trying to get them up for a while. I'm going to copy your steps though and do up our logo tomorrow.  I really appreciate all your help, this is more than I could have hoped for to be honest  : )

Joseph Pizzolatto

I can bring up the Windows -> Docable Dialogs -> colors (or colormap as well), but I don't get the colors along the bottom like you do. I've been trying to get them up for a while. I'm going to copy your steps though and do up our logo tomorrow.  I really appreciate all your help, this is more than I could have hoped for to be honest  : )

Joseph Pizzolatto

Maybe this:

More info here: http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Anatomy.html

oh... eerrrr I must never let anyone know I thought I had been looking at GIMP the whole time, and that I just had a very Very different default tool setup... yes, must -never-, let **  anyone  ** know....

but... I am actually Much more happy to be doing this back in inkscape again : )

Soon I will do this I mean, school is tricky all online, I will respond when I use this and thanks again : )

still working on it guys, finally got back to doing it more and I easily did the above steps, it was... well it was easy as hell thanks, will update when done

I think this part is done, I am happy with this and will test it on a number of materials later. This is for a school 'maker space' type of place that's free for student use. I will also use this for an appreciation plaque for a really dedicated teacher. I'm a student and now also a student-employee there and I get to help people all the time! Thanks to all you guys for helping me, I really appreciate it very much. Stuff like that feels really good : )

actually I don't seem to be able to upload the file

it has really thick lines and I used Lines instead of Dots for my 'greyscale to newsprint'. I thought fewer fat lines would be handled better and not make weak spots as much. I made the range go from 20%-80% so the light parts are still visible and the 'solid' parts are not just empty sockets on the engrave.

Next I'll try and put it back into inkscape and make it into paths, that will be the best possible final result (infinite scaling and resolution independent)

Final Post barring finished pics (I hope)

Guys, again I thank you all for your help. Everything seems done, I will laser a test print of the entire appreciation plaque in a day or two. If all goes well then I'll do the real one just after and then finish it. Thanks again for all your help with this part of that!!

Final Post barring finished pics (I hope)

Guys, again I thank you all for your help. Everything seems done, I will laser a test print of the entire appreciation plaque in a day or two. If all goes well then I'll do the real one just after and then finish it. Thanks again for all your help with this part of that!!

Final Post barring finished pics (I hope)

Guys, again I thank you all for your help. Everything seems done, I will laser a test print of the entire appreciation plaque in a day or two. If all goes well then I'll do the real one just after and then finish it. Thanks again for all your help with this part of that!!