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Thread: Converting programs for Engraving Manual Method and Adobe Photoshop

  1. #16
    Normal maps? I seek enlightenment, O guru. <--not sarcasm- I'm not good at 3D
    Oh yeah. Halftones. This is a process where you only have black to work with (as we do) and you use different-sized dots to make up the image. If you use the 'halftone' filter in any program you like; you're probably going to end up with an image that looks like it came from an 80s newspaper. Nevertheless, what we do is halftoning, but with a different emphasis these days...for lasering, all the dots are the same size and it's the _distribution_ of all these identically-sized dots that make the picture.
    I'd recommend having a click on the link above, because it's useful information
    Last edited by Darren Null; 08-28-2008 at 10:51 PM.

  2. #17
    Halrighty. Test time.
    We have:
    1) original
    2) etchtone (photoshop filter- poor man's photograv...couldn't be arsed to fire up photograv and photoshop was already open)
    3) halftone. You will notice that there's all sorts of grey in there. I haven't found a halftone filter that just deals with black and white, although there undoubtedly is one.

    10 centimos says that number 2 gives you the best burn, whatever it looks like on your screen. Any takers?
    EDIT: And if you run #3, you'll have to run it through another filter to get it right.
    EDIT AGAIN: Oh cock. I got the size of the etchtoned picture (#2) wrong and it's smaller than the other two. It'll still burn better, but it's not scientific anymore. Damn. Frottage. Etc. Long evening.
    EDIT AGAIN AGAIN: Resized 'em all. That's better. We have SCIENCE! again.
    EDIT AGAIN AGAIN AGAIN: No we don't. It's still bloody smaller. Hmmm. Science will have to wait till tomorrow, methinks. It'll still be a better burn than the other 2 though. Try it.
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    Last edited by Darren Null; 08-28-2008 at 10:53 PM.

  3. #18
    I tried the "Gold" action with two different pictures. Neither of them gave me great results on the laser. However, that's not the point.

    For a newbie, figuring out what a picture needs to look like on screen before sending it to a laser is 75% of the battle, and Frank's Photoshop application got me at least 80% of the way there. And then there's the material being engraved. I tried a pretty good picture on finished an unfinished wood. I was surprised by how much better the imaged looked on the unfinished wood. The finished wood gave an unexpected effect - the areas that burned deep looked good, but the lightly burned areas were brighter than the natural wood - probably because the laser didn't actually burn wood, but instead altered the finish. The lighter areas threw off the shading for the entire image.

    All of this is to say it takes a lot of practice and experience to laser images reliably. I'm greatful to guys like Frank, though, who help speed the process along.
    Robert Mitchell

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  4. There are a variety of halftone digital screening techniques out there. The ones that Photograv uses is a stochastic half tone. And like you said it uses the same size dots.

    Before getting into lasering I was a photographic printer, an old days type enlargers and chemistry and darkrooms! (boy I am old!).
    I did most the printing and didn't deal too much with the scanner guys, they where a whole different breed. (now I wish I paid a bit more attention!)

    These guys really worked their magic in getting quality work to the presses.

    I can understand that if you have dots all the same size and they happen to be the same diameter as your lens resolution. It makes life easy on the laser as long as your exactly in focus across the board and consistant on the burn.

    I can see issues arising as different substrates such as wood or plastic that there would be more "afterburn" as the laser "dots" the material as opposed to laser brass metal or marble. (take a cigarette for example and touch it to paper, the paper burns after the cigarette is removed) So now that dot is a bit bigger.

    I'm not sure why if I created a screened halftone and the the none of the dots are smaller than the diameter of the lens that it wouldn't work. I burn line art all the time and isn't that really what a screened image is? (black & white)

    I'm sorry if I sounded like a "know it all" because believe me I don't!
    I just wanted to share a different side of imaging that some in the forum may not have experienced.

    One thing that has confused me is if Photograv uses the same size dots, why do they tell you not to rotate the "engraved file"? If you run your laser at a slower speed to make the x and y planes more similar why would rotating the file before you burn it make a difference?

    Can we address the laser through a profile like you can with a color printer?

    Someday maybe there will be more profiles that we can add and modify.
    I guess there are a few options now as you can pick in the drive photo or clip art. Wouldn't it be great just to check in the drive Photo wood, photo marble etc.

    I know I had a problem awhile back on one laser because of that. I run a dye sub printer off the same computer as that laser and somehow the defaults got changed and it converted my file to the dye sub profile when it was sent to the laser, that created a big headache until I discovered it!

    I want to do more images and I'd like to understand how to have more control on their outcome with less waste and testing. I'll keep plugging away at these conversions as I find time, but for now I to use Photograv because it's quick and easy.

    I really do appreciate this forum as we all have different experiences in what we do and it's great to have this forum to share it with others.

  5. #20
    I can see issues arising as different substrates such as wood or plastic that there would be more "afterburn" as the laser "dots" the material as opposed to laser brass metal or marble. (take a cigarette for example and touch it to paper, the paper burns after the cigarette is removed) So now that dot is a bit bigger.
    And there you have put your finger on the nub of the matter (-1 point to me for mixing metaphors). Making papers, it's essentially an instantaneous operation. *THWOCK* and the page is done. With lasers, to make bigger dots, you have to apply heat to a small area for longer; and even if it doesn't catch fire, it's going to look different than (to?) the smaller dots. Blacker, maybe.
    With photograv, all the dots are the same size, so all the black areas are treated the same and should look the same. The exception, of course, is where you have a lot of black together and adjoining pixels will be getting the heat from their neighbours.

    I'd quite like to see a halftone filter that deals with just black and white. All the ones I've seen are 8-bit greyscale. With lasers, you burn a hole or you don't.
    if Photograv uses the same size dots, why do they tell you not to rotate the "engraved file"?
    I have no idea. Anyone know?

  6. #21
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    Quote Originally Posted by Frank Corker View Post
    Well things are looking pretty positive then. This is the original script that Rodney came up with. The actions are just a way of doing it automatically without having to give it much thought.

    1) Convert to 8 bit greyscale (image/mode/greyscale)
    2) Resize the image to the size its gonna get engraved using 150-300 ppi (150 for less detail)
    (image/image size)
    3) Bump up contrast and brightness about +25 in
    both cases - you dont want the pic to be insipid areas of medium grey. (image/adjusyments/brightess-contrast)
    4) Heres the VITAL part - use unsharp mask at 500% and a radius of 3-5 pixels - threshold 0 - this will exaggerate edges radically , but thats what you need. In fact you can do this and then STILL add another unsharp mask at 150 % , 1pixel and 0 threshold AFTER the 1st unsharp if you want even more edge detection
    (filter/sharpuen/unsharp mask)
    5) Convert to a bitmap using 125-150ppi and a diffusion pattern. (image/mode/bitmap)
    5) laser.
    If you're working with a "negative" medium (e.g. black granite), what's the optimal point in this sequence to do the invert?

    I don't have any Photoshop (except maybe the freebie version that came with one of my cameras), but I'm going to take a look at the API for PhotoPaint and see if I can cobble up a VBA script for some or all of it.
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  7. One more thing to try, instead of using the "filter" halftone effect,
    open an image in photoshop, convert to 8 bit grey scale, now under the image dialog box pick the bitmap option. This should open up a dialog box that deals with halftones and dithering. It gives you a few options, you can even use custom screens!

    When I get a chance I'll play with this a bit and post results. If someone tries
    this let us know your results!

    Thanks,

    Marty

  8. #23
    If you're working with a "negative" medium (e.g. black granite), what's the optimal point in this sequence to do the invert?
    After it's converted to 1-bit.
    When I get a chance I'll play with this a bit and post results.
    If you try it, can you use the 'original' eyes photo? I'll photograv that too, and we can have a real test.

    Done. Attached is a GIF representation that's pretty accurate. BMP in the zip file for purists, but it looks the same. I swapped to GIF because the filesize is smaller because there's only 2 colours (30-odd K plays a 200K JPEG for the same image).

    Yup, it looks sucky on screen, but the image below will give the best results if you burn it.
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    Last edited by Darren Null; 08-28-2008 at 11:39 PM.

  9. #24
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    I managed to get everything working and ran a trial. I had actually been fiddling with photos today so had another piece I had done with pictures I had worked on in CorelDraw.

    The top two pictures are done in CorelDraw using the following method:
    Effects - Adjust - Desaturate (converts to greyscale).
    Effects - Adjust - Hue/Saturation/Lightnesses - set saturation to -100.

    With the picture on the left I then adjusted the brightness of the picture.

    Using the Gold Method, the bottom two pictures, I did not make any further adjustments to either of the pictures so the picture on the left is a bit dark. The wood used in the Gold method is also slightly darker.

    Basically I would definitely try the Gold method first before going through the hassle of fiddling around. I had tried the step by step Gold method before but had shelved it for a "free time day" which finally arrived!!

    Thanks Rodney and Frank
    Carrol
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  10. #25
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    The method i posted is a "cheap mans" version of photograv , kudos to Frank for formalizing it in an action.
    Results using it are going to be variable as some of the steps I proposed will not work 100% on all pics , I have tried various images both ways and some are better with photograv and some better with the photoshop method.
    Key to using any of these methods is the original artwork and what it looks like in greyscale after the colour has been removed. If the pic is insipid and does not have a big dynamic range , ie is mostly greyish , you aint gonna get great results.
    At the end of it all , there are sooooo many variables that are going to determine your results , is the pic in focus , is it decent resolution , does it have defined edges , what laser power , what spot size , does it need contrast enhancement , does it need the unsharp mask , what materials , how deep must it be lasered and so forth.
    Even photograv , albeit it does have variables you can set , is not always guaranteed to work either.
    But at any rate , all thanks to Frank for his sterling efforts and for subscribing to the spirit of sharing that makes the internet great ............
    Problem for a lot of us is that we dont have Photoshop , so I was fiddling in Corel for a similar type of "action/script" but havent had a lot of success but will continue working on it.
    My problem is that we don't do a lot of giftwork , so transferring pics to items is not a priority , but we do however use these methods BIG time for vector clipart (avoids hiden lines , fade islands etc) and often use it for once off quick and dirty engravings of bitmap colour logos we get from various companys.
    I have actually also been fiddling with my lasers inbuilt photo engraving thingy (Laserpro.Gcc) and to be "frank" , so to speak (sorry couldn't resist) its very very good (latest spirit driver)
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  11. #26
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    I for one can't thank Rodney enough. I use his method on a daily basis. I'd like to take off my hat to Frank for doing the works also.
    However, as a side note, I shorten the steps myself by not leaving Corel Draw. I've tested Rodney's method both ways and can't see the advantage to going into PhotoPaint. I know the steps by heart and have for probably a year or more. Takes only a minute or two.
    I change a lot of Vector art into a bitmap before lasering.
    These are the modified steps.
    (1) Choose the image and convert to grayscale 300dpi.
    (2) Under Bitmap, resample to the proper size.
    (3) Under Effects / Adjust/ Brightness, Contrast, Intensity bump up Brightness 25, Contrast 25, Intensity 0 (these setting will stay after you do them the first time)
    (4) Under Bitmaps / Sharpen / Unsharp Mask / percentage 500. Radius 2.

    I know it's almost exactly the same but I don't have to launch into Photo Paint to do it this way.

    Thanks again to Rodney!

    I've compared a photo done with the new Epilog drivers Stucki, Floyd, blah blah blah and " The Gold Technique" blows them away!
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  12. #27
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    The Gold Method most definitely will work with a very high percentage success rate. I think the skill comes in choosing the level of brightness for the picture you intend to engrave. Before running the actions in photoshop, level out the settings and save, after that it should come into it's own.

    Earlier in this discussion the halftone effects were being mentioned, on granite I actually like that effect, especially if the engraving is done on a larger piece of granite. It seems to ward off collections of dirt in the final product and less active to grease from the fingers. For something that needs to be seen close up, then it needs to be refined in one of the normal methods (photograv etc), but from a distance I think halftoning. It's just so mind boggling that to achieve that goal.

    All said and done, generally the format is, quality picture - quality result.

    I'd also like to say thanks to everyone for participating, the wealth of experience that we all have, collectively is amazing. Mmmmm sounds Star Treky!
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  13. #28

    Works on a Mac too!

    Well, Frank, I sort of got to use your automatic action... I am running a Mac. So, I copied the steps and ran the recording thingy and voila! It worked very well on the Mac!

    Even though it loaded onto my pc with Photoshop 7, it wouldn't run, so I'll try to do it manually there too.

    What a timesaver! Seconds instead of minutes, but better yet, no brains required... great for us geezers who shouldn't overstrain what little we have left. Thanks for pointing out the action command! I've used Photoshop since the first version, knew "actions" existed but never bothered to play with it.

    Of course, until I got a laser, I never had a need to repeat actions exactly according to a formula.

    cheers, dee
    Epilog Mini 18/25w & 35w, Mac and Vaio, Corel x3, typical art toys, airbrush... I'm a Laserhead, my husband is a Neanderthal - go figure

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  14. Great!
    It's good to see everyone teaming together for the good of the group!
    There are so many people out there with different exprience and to have them step up to the plate really makes a difference.

    Engraving photographs is one of the hardest things for an engraver to, and now with the help of Frank, Rodne and all the others we all have a better understanding of the process.

    No system will be perfect, but now we tremendously increased the odds of
    making a quality engraving! Way to go guys!!!!

    For those with photoshop here are a couple sites that have actions to download. There are tons of them out there as well as tutorials for making better grey scale conversions.

    What I find helps in working towards better images is, when you have an image that you think burns real well, save that image and use it as a bench mark when converting other images. It's nice to have a visual reminder while you are converting.



    http://www.atncentral.com/download.htm

    http://www.russellbrown.com/tips_tech.html

    http://www.thelightsrightstudio.com/photoshop-tools.htm

    For those of you that don't have Photoshop or a photo manipulation program there is an open source program out there for free, yes free! That I have heard good things about. I run Photoshop so I haven't tried this out, but I thought I'd pass it on in case there is some interest.

    http://www.gimp.org/

    Keep up the good work Creeker's

    Marty

  15. #30
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    Hey Darren,
    It says in the Photograv manual that the converted file is a binary file and these types of files don't like to be manipulated or you lose the subject clarity (or something like that).
    Rich.

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