Photograv

[Runar Schmidt]

Hello, I just found this forum yesterday and have had many hours of interesting reading.

I live in Sweden, and a couple of months ago I bought a Mercury Laser engraver 25w. Together with the machine I use Flexi8 Family and Coral Draw x3.

I’ve been getting various results with my photos and I don’t really know how I should do to get a better result. When I engrave photos I use Coral Draw.

I am trying mainly to engrave photos on stainless steel. The problem is that it either ends up getting too black or nothing at all. There is nothing in between. (If I use a vector file the result is perfect)

I’ve seen in many threads that you use photograv and I would like to know if this is the solution for me or am I doing something wrong in Coral Draw.

I hope somebody can give me a good advice on this problem that I have.

Best regards
Runar

[Mike Hood]

I also use Photograve and Corel X3. What resolution is your image that you start with? I've found that shooting (or scanning) in the SAME resolution that you're usig in Photograve really improves the results.

Also... Resize the image in Photo Paint or Adobe BEFORE running it through Photograve. The sequence in the way you process these really make a difference in the final output.

[Bob Keyes]

Dear Runar,

Here's what I can tell you from a neophite's perspective. I tried for months and months and many $$ :confused: worth of material to get a good picture without Photograv. I finally bought it ($$ouch):eek:. What a difference. Now I can do any picture with much confidence.:o

This doesn't mean that you don't have to experiment some. As has been said, the sequence of events is important. Get the size, contrast (needs to be high), and dpi right in your program of choice. Then put it into Photograv and your picture will be near perfect.

I don't know if Photograv will solve your problem or not, but it sure solved mine, and it was a bad one. I'm happy.:)


Hello, I just found this forum yesterday and have had many hours of interesting reading.

I live in Sweden, and a couple of months ago I bought a Mercury Laser engraver 25w. Together with the machine I use Flexi8 Family and Coral Draw x3.

I’ve been getting various results with my photos and I don’t really know how I should do to get a better result. When I engrave photos I use Coral Draw.

I am trying mainly to engrave photos on stainless steel. The problem is that it either ends up getting too black or nothing at all. There is nothing in between. (If I use a vector file the result is perfect)

I’ve seen in many threads that you use photograv and I would like to know if this is the solution for me or am I doing something wrong in Coral Draw.

I hope somebody can give me a good advice on this problem that I have.

Best regards
Runar

[Rodne Gold]

Photograv is the way to go if you want to bypass jumping thru hoops in Corel and of course photograv bypasses the lasers own dithering and 1/2 tone driver. The photograv output is actually not a greyscale thing and you wont use the B&W part of the GCC driver , you will use plain colour mapping.
Even if you get it right in Corel , theres no guarantee you will get it right in the lasers B&W (raster) driver or get consistent results using it , with photograv you get an approximation of what you will actually get on the material before you start as well.
You can either let photograv do it automatically or you can have control over all the steps photograv takes , either way you gonna get it right 98 % of the time. I think the package is pricey , especially since there has been no developmental work on it for the last few years and the list of materials it has profiles for is limited. $199 or $129 would be a fairer price to pay for it than $399 or so. However it will save you hours and pay for iotself pretty quick after just a few pics. Also great for clipart with gradients , complex paths , many colours or hidden vectors and so forth , in fact its pretty good for ALL raster type enraving.
the fly in the ointment is that you CANNOT resize , rotate or mirror the object once its gone thru photograv.

[Runar Schmidt]

I don’t have Photograv yet but I wonder if it could help me with my photo problem or if I could solve the problem in Corel X3 with some adjustments and save some money.

I have never heard of Photograv before that’s why I’m asking if its good.
The resolution of my image is 300dpi.

/Runar

[Pat Kearney]

I used photgrav for over a year now and I am extremely pleased with it however, I mostly engrave photos on wood and have never tried stainless steel.

[Bill Cunningham]

I have used the halftone function of my epilog for photos in marble, and stainless (using cermark) with very good results.. Photograv turns those bitmaps done with 'very good' results into GREAT results...
I'm not sure just what half toning is available in the mercury, but if simple rules are followed, you should be able to get very good result..
#1 NEVER use .jpgs (their almost always fuzzy) If you 'have to use a .jpg, it should be a 'virgin' .jpg.. i.e. one that has been taken at the highest camera resolution possible (never etch a 640x480 photo) and must NEVER have been worked on and re-saved as a .jpg (they only get crappier every time you save them)
#2 Artwork should be at least 300 dpi 'at the size it is to be etched'
#3 Etch at either 300 dpi, or a multiple of 300 dpi, or a multiple of what ever the original scanned image was (I use 600 dpi for both marble, and stainless on images scanned at 300 dpi)

The vast majority of problems etching photos into stainless or marble, is lousy original picture quality.. Remember your screen is only about 96 dpi and makes just about 'anything' look good.. Your laser on the other hand etches in 'reality' Kind of like the problem now facing the folks who work on T.V. for a living.. Hi Def video, is now showing the world 'exactly' what they look like, zits hidden under makeup and all, creating a real 'bonfire of the vanities'.. Oh, and trying to etch into glass or wood using the built in halftoning abilities is a waste of time and material.. You either spend hours honing your dithering skills in photopaint..etc.. or buy photograv and do your pictures in minutes most times..

[Rodne Gold]

Just as a matter of interest , you are probably NEVER going to get great images on stainless steel using Cerdec or marking paste , the reason is that it cannot hold anything barring the grossest of resolutions due to the way the marking paste acts on the metals ,
There is what is called dot gain , and its horrendous.
Imagine dropping a blob of ink on blotting paper and watching it spread out , simplistically , thats what dot gain is.The dots overlap too much so the detial of the dots just blur into one big mess.
You can do a few things to improve this , firstly scan and laser at 120 dpi or less , to 75 dpi.
Secondly , apply the cerdec with an airbrush and use a VERY thin even layer , a brush wont work here
Thirdly , do not "overburn" the cerdec , use a fairly fast speed at full power or at least try it
Fourthly check you are PERFECTLY focussed on the part so you get the smallest spot size.

300 PPI scanning is often overkill , the laser , due to its spot size cant even manage 250 TRUE dots per inch and considering 1 scanned pixel does not equal one fired mark (or dot) but rather a matrix of marks , the true resolution is pretty near 100 pixels per inch in terms of what can be engraved.

Imagine a pixel that white , thats easy , the laser doesnt fire , imagine a pixel thats black that easy too , the laser fires.
But now imagine a pixel thats grey , the laser cant "sort of" fire to make grey , it can ONLY make a black or white mark.
So the only way to represent grey is to scatter teeny black marks on a white surface , the closer they are and the more of them , the darker the grey.
So - you can see that one pixel you have scanned CANNOT be just represented by one lasered dot , it has to be a cell or matrix of dots. Physically the laser can at best only do 300 discrete dots per inch and if you have a 3dot by 3 dot matrix , you can see the laser needs 9 physical dots to represent one scanned dot (3 along , 3 down) so it can only possibly represent 100 pixels per inch correctly.
There are a lot of other factors affecting how photos will come out on various materials , but reducing resolution helps a lot in getting better results and speeding up cycle times.
If you dont beleive the resolution thing , print a 150 Pixel per inch greyscale image on a laser PRINTER and then do one at 100 PPI (print the 100ppi image at 300 dpi or on a 300 dpi laser)
I can guarantee you even the 100 PPI will be scads better than you will ever get on a laser engraver even if all things were spot on.
DO NOT confuse printer dpi with pixels per inch in the image , the printer isa physical capability and the other is measure of detail.
The only real conclusion I have ever come to regarding the best strategy for lasering pics is that there is no real hard and fast rule of what works , its so driver/material/platform dependant
Even if my perspex or marble settings work for a similar laser , there might be material issues tween regions or suppliers that make detailed setting instructions not so valid and give bad results. When engraving various materials for photos , you will get sweet sopts , a combo of speed , power and resolution that makes it all good , and the only real way to get this is to spend some time on documented experimantation.

[Bill Cunningham]

This image was supplied as a fairly low res .jpg, This is all the person had.. It was burned into a stainless plate at 600 dpi, ( I burn at 600 dpi because it satisfies 'me' and I've never seen a satisfactory photo in stainless at anything less) 100% power, and about 10% speed (can't remember exactly, I don't have my notes handy) on a 35 watt machine. As Rodne says Focus is 'critical' if your off just a bit, or trying to burn along the edge of a radius, the cermark will not work correctly, and the stainless must be 'Clean' No fingermarks, No oil, washed down with alcohol or acetone, sometimes both.. The cermark, in this case, was sprayed on from the can with two coats. then washed off with high pressure water (1500 psi) after lasering.. The customer was MORE than satified, even though I would have liked to have a higher res picture..
It does not take much to satisfy a non graphics person as a customer. They do not have the same expectaions that someone who works with this all the time.. It does not 'have' to be sharp enough to count the dots. It only has to be as sharp as the supplied artwork is capable of producing. That is usually enough to satisfy the customer who hands you a .jpg to work from.. You can waste as much time as you want tweeking, primping, and testing.. The average person that walks through your door will never see or appreciate the extra work, unless they have another piece 'with' all the extra work to compare it to.. You do the best that you can, and charge a fair price.. If the customer likes what he or she sees, then you have done your job right! Experiment with your machine in your spare time, what work well for one person/machine, may or may not work well on yours...

[Bill Cunningham]

In the case above, the customer brought me in a piece of stainless he wire-wheeled clean, and drilled some holes in it..It was not processed in Photograv. The greyscale was simply run using the photograph mode in the epilog driver.. The Piece was later screwed into a stainless cross, and mounted as a roadside memorial.. I drive by it just about every day, and it has not faded a bit.. Hopefull it makes people think when they go through this particular intersection which has killed several over the years..