Removing text from a finished lithopane

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TimSchubach
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Removing text from a finished lithopane

Post by TimSchubach »

I have a client who asked me to make a lithopane from a photo that had some text in the lower right-hand corner. The text was clear and not too detailed, so I followed the same steps I always do to create the lithopane. The text was black, so that part of the lithopane was raised.

When the liothopane was finished, the text was very hard to read. Even knowing what it said, I had a hard time reading it. So I got the OK from my client to do something different. I used used PaintShop Pro to remove the text from the original photo, and I saved a copy of it. Then I used PSP to add the text back, using a font that had even less detail, and was a little larger. However, the results were only marginally better.

My client and I talked, and decided to just remove the text from the lithopane altogether, which I thought would be fairly easy to do. I opened the saved copy of the lithopane without the text, and cropped a section from it where I had added the text back. I generated a tool path for that section of the lithopane, remounted it, and started cutting.

On completion, some of the text had been removed, but not all of it - not nearly enough of it. So I re-positioned the bit to cut just a little deeper, and ran the tool path again, but with the same results. I've done that three more times, but there is still some remnants of the text that I can't seem to get rid of.

Am I doing this the right way, or should I just re-cut the whole lithopane again? I'm tempted to re-cut it using the same piece of material, just using the photo without the text as opposed to starting all over again with a new piece of Corian ( which is pretty hard to find ). Any suggestions would be appreciated.

By the way, the text that I'm trying to get rid of will be engraved into the frame I'll make to mount the lithopane instead of making it part of the lithopane. So it won't be lost.

PaulRowntree
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Re: Removing text from a finished lithopane

Post by PaulRowntree »

I don't have a direct answer for you (sorry) but editing compressed images that used 'lossy' methods (like jpg) is often difficult to do accurately. Anti-aliased images are also tough to work with. Compression can turn sharp edges (like text) into slightly blurred edges, with ripples extending out many pixels beyond the original edge. I think it is due to the fourier algorithms used. Slight intensity changes that are barely visible on the image are very visible in STL's and toolpaths based on the image.

Can you just sand the backside of the litho?
Paul Rowntree
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Ms Wolffie
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Re: Removing text from a finished lithopane

Post by Ms Wolffie »

I am not sure from your explanation whether the text was messed in with original part of the image or separate.
If it was separate it is a simple act of selecting the part you want to keep and crop to selection.
Then you enlarge the canvas, fill the white part with the background colour and again crop to size. Text is gone.
If the text was part of the image, it is a bit more complicated.
Using the clone tool, select a part of the background without the text and clone it over the text part.
Then you dodge the edges to make them blend in.
WithText.jpg
My3GreatGrandDaughters01.jpg
Text gone.
To answer your second question.
I think you will spend a lot of wasted time repositioning the workpiece exactly where it was originally.
Cheers
Wolffie
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TimSchubach
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Re: Removing text from a finished lithopane

Post by TimSchubach »

Hi Wolffie - thanks for the response. Since I was not the photographer, I can only assume that the text was added afterwards in something like PSP. I didn't have a problem deleting the text from the .JPG file and adding next text, but as I said, in neither case did the text "pop" and it was not clear enough to read. So what I am trying to do is run a new tool path over the part of the litho where the text is in order to remove it.

Normally, because that's the way I was shown to do it when I bought my machine, I locate the origin in the center of the piece instead of one of the corners. Once a litho has been cut, I obviously cannot do that if I've already removed the piece from the bed of the CNC, so in this case, I'm locating the origin in the lower right hand corner where the text that I want to remove is located. I had serious doubts about whether I'd be able to locate the piece correctly, but as far as I can tell, I have. If it's off, it's off so little that I don't notice it. I just don't understand why that new tool path still leaves part of the original text. Not only can you see it, but you can feel in also.


Paul, thanks for your explanation as well. However, I don't understand what sanding the back of the litho would accomplish. I do, though, believe you are correct at least about the text in the original .JPG file, which I did not notice until after I had already run the tool path. When I enlarged the original .JPG after the fact, I noticed that the text was "pixilated" and did not have a sharp, clearly defined edge. My bad for not having checked that before I cut the tool path. However, the text that I used as a replacement DID have a nice clean edge, and I was very surprised that it turned out as badly as it did.

I think what I'm going to try, just to satisfy my morbid curiosity, is to to cut the tool path for the .JPG file without the text over the litho with the modified text, just to see what happens. I've kind of resigned myself to the fact that I will likely have to sacrifice another piece of Corian and cut an entirely new piece on the assumption that my "cut-over" approach will not be totally successful. But I do have to try, just because. If it does work, great. If it doesn't, well, that's what I'm expecting.

Thanks a lot for your feedback.

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Re: Removing text from a finished lithopane

Post by PaulRowntree »

TimSchubach wrote: However, I don't understand what sanding the back of the litho would accomplish. I do, though, believe you are correct at least about the text in the original .JPG file, which I did not notice until after I had already run the tool path. When I enlarged the original .JPG after the fact, I noticed that the text was "pixilated" and did not have a sharp, clearly defined edge. My bad for not having checked that before I cut the tool path. However, the text that I used as a replacement DID have a nice clean edge, and I was very surprised that it turned out as badly as it did.
Sorry, I didn't phrase that correctly. I was wondering if instead of trying to remachine the text region off, which in my view may not eliminate the jpg-created ripples distant from the text edge, what if you just tried to sand the entire machined side (not the back side as I wrote). The whole image would get lighter when backlit, but it would be a uniform background then.
Cheers!
Paul Rowntree
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Ms Wolffie
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Re: Removing text from a finished lithopane

Post by Ms Wolffie »

TimSchubach wrote:By the way, the text that I'm trying to get rid of will be engraved into the frame I'll make to mount the lithopane instead of making it part of the lithopane. So it won't be lost.
It would be interesting to see the picture in question.
I think I misunderstood what you are trying to do. I presumed you wanted to delete the text and carve it in the frame instead.
I could not work out why you wanted to do this:
"I used used PaintShop Pro to remove the text from the original photo, and I saved a copy of it. Then I used PSP to add the text back, using a font that had even less detail, and was a little larger. However, the results were only marginally better."

BTW, PSPX2 is my preferred program.

Cheers
Wolffie
Cheers
Wolffie

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