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View Full Version : Photograv Dithers..then Epilog uses Standard in addition..wondering about effect ?



Larry Bratton
05-28-2010, 8:40 PM
This may be a stupid question but I'll chance it.
When raster engraving with the Epilog driver, the default is Standard Dithering. If one has used a program such as Photograv to dither a photo or other prior to printing, would the additional dithering applied by the Epilog driver have an adverse effect on the engraving? Just seems redundant to me. Does Photograv compensate for this?

Rodne Gold
05-29-2010, 1:02 AM
Photograv's output is 1 bit - IE black. Will your driver dither black?

Frank Corker
05-29-2010, 6:58 AM
When you use Photograv you have to enter you machine details, Maybe it has already been factored in, Epilog newsleter are now recommmending Photlaser Engraveplus but I have never had the oppotunity to try it.

Dan Hintz
05-29-2010, 8:32 AM
When raster engraving with the Epilog driver, the default is Standard Dithering. If one has used a program such as Photograv to dither a photo or other prior to printing, would the additional dithering applied by the Epilog driver have an adverse effect on the engraving? Just seems redundant to me. Does Photograv compensate for this?
Any extra dithering step after PG will effect the final image, though maybe not to a large enough degree to be noticeable. PG exports as a 1-bit dithered image already.

Rodne Gold
05-29-2010, 8:52 AM
Dont engrave PGRAV output as a photo. it has no greyscale.

Larry Bratton
05-29-2010, 9:18 AM
Dont engrave PGRAV output as a photo. it has no greyscale.
I'm not sure I understand this. Are you saying not to use any other dithering method in the driver other than standard? Their is not an option for No dithering, which seems to be in error. If it were an option, then one could use other methods and be assured that the output would not be affected.

Larry Bratton
05-29-2010, 9:38 AM
When you use Photograv you have to enter you machine details, Maybe it has already been factored in, Epilog newsleter are now recommmending Photlaser Engraveplus but I have never had the oppotunity to try it.
I guess that's part of my question Frank, does Photograv compensate for that someway? Could this possibly be a reason for poor output from an Epilog using PG? (or at least a variable in some cases)
I too saw the announcement about the Engraveplus, and watched the propaganda video. I have not seen what the cost of this program is as of yet, but based on the supposed wonderful results they achieved, you can bet it won't be cheap.

Larry Bratton
05-29-2010, 9:39 AM
Photograv's output is 1 bit - IE black. Will your driver dither black?
I have not a clue. I assume so.

Darryl Hazen
05-29-2010, 9:43 AM
Has anyone seen this new software from Epilog? Just received the info this morning. Looks very promising. No price listed.

http://www.epiloglaser.com/photo_laser_plus.htm

Scott Shepherd
05-29-2010, 10:17 AM
Has anyone seen this new software from Epilog? Just received the info this morning. Looks very promising. No price listed.

It's a product of Cadlink, their product line is "Engrave Lab" and this photo product is listed at $495.

Larry Bratton
05-29-2010, 11:03 AM
It's a product of Cadlink, their product line is "Engrave Lab" and this photo product is listed at $495.
Choke!!!!!! Are you saying the new software is listed at $495. I looked on their website and saw the Photolaser Plus but didn't see a price. They sell through distributors too, so that may be where we have to find the real price.

Dee Gallo
05-29-2010, 11:10 AM
Tempting, but high priced... I don't want to be the guinea pig, but would love to know just how much you have to prepare the photo to make it work well. Seems like they used high quality pics, without the usual washouts or funny stuff we have to remove before they can be used. And I don't see a background removal feature, so that would still have to be done in PhotoShop/ CorelPaint anyway. I'd like someone to take a crappy pic and run it through... THAT would sell me if it worked!

:) dee

Larry Bratton
05-29-2010, 11:22 AM
Well, obviously we have gotten off of the original topic. If anyone would like to respond to that it would be good. Maybe we can start another thread on the software. Thanks

Rodne Gold
05-29-2010, 1:39 PM
A photo will have shades of grey , the driver would interpret this as black dots with spaces - IE it would use a dither pattern to space these black dots in a certain way.
However Pgrav has already done this and is merely sending the black dots and spacings for engraving - your driver should see no shades of grey at all , merely solid black dots/areas and it would not need to dither at all. All you should do is engrave it as if it were a drawing that had black areas.

Larry Bratton
05-29-2010, 1:51 PM
A photo will have shades of grey , the driver would interpret this as black dots with spaces - IE it would use a dither pattern to space these black dots in a certain way.
However Pgrav has already done this and is merely sending the black dots and spacings for engraving - your driver should see no shades of grey at all , merely solid black dots/areas and it would not need to dither at all. All you should do is engrave it as if it were a drawing that had black areas.
So, the bottom line is that the dither that Epilog calls Standard and is the default would have no adverse effect on a Photograv processed image?

Rodne Gold
05-29-2010, 2:02 PM
Well , I can't answer that 1000% - I would assume that the driver should engrave it as it would any other purely black logo or drawing - Your driver should have a normal mode where you can set colours etc - and a photo/greyscale mode - just dont engrave it in photo/greyscale mode. Send it as you would a normal CDR file.

Larry Bratton
05-29-2010, 2:30 PM
Well , I can't answer that 1000% - I would assume that the driver should engrave it as it would any other purely black logo or drawing - Your driver should have a normal mode where you can set colours etc - and a photo/greyscale mode - just dont engrave it in photo/greyscale mode. Send it as you would a normal CDR file.
Epilog's driver is lacking in this respect. No settings of this type exist. The dithering options are Standard, then Jarvis, Floyd Steinburg and a couple more. That's it. I assume the machines that you have do have the options in the driver that you refer to. I was just wondering if this was something that Epilog should address.

Dan Hintz
05-29-2010, 7:31 PM
Larry,

I think it's safe to say that if no dithering is necessary (i.e., the image only contains black), no dithering is added, regardless of settings. You should be able to choose Standard, Jarvis, or 50 other types and it will not effect the image. The dithering algorithms are under the assumption the input image has shades of gray... areas of pure black in grayscale images go untouched by the dithering algorithms,and so will be the case here. Each dot from PG is already pure black, so they will remain untouched.

Frank Corker
05-29-2010, 7:36 PM
Could this possibly be a reason for poor output from an Epilog using PG?

Larry I didn't agree say or agree that you get a poor output from Photograv. To the contrary, I think you do get a good result, on wood and acrylic for certain. I did find that on glass, using an 8bit greyscale image at 300 dpi the Epilog driver did it's job just fine without the use of Photograv.

I think the reason for that is that the Epilog driver seems to convert to a good conversion on it's own for that substrate. A nice halftoning pattern, which if correctly manipulated will always give a good result, after all that is what you see with a newspaper.

As to how much does the driver affect the way the image, I'm not certain, however with a well processed image, the Epilog lasers will produce a good result. I am a little biased here, having one myself, but I am trying to be objective.

An image processed first through photograv and sent to the laser will produce a good image if done properly on glass. An image not processed through photograv if processed properly using the Epilog driver will also produce a good result, without the need for photograv. However on close inspection of two samples done, the photograv one will not be as uniform as the halftone dithered image from the Epilog driver, but unless you are looking with a magnifier, the results may appear similar in quality.

Hope that makes some sense. How will you ever be able to tell if photograv and using the Epilog driver do alter Photograv's conversion? Unless you use a different type of laser, that's the only way, then the question will be is it the other laser's driver that is altering it. Conundrum.

Using Jarvis stucki etc and just normal on the Epilog. One of them seems to engrave lighter, the other a little darker. I tend to just stick with normal as the results are generally pretty good. If I'm unhappy with that, then I might give the others a chance, but it has been very rare.

Larry Bratton
05-29-2010, 9:19 PM
Thanks Frank, Rodne and all for your replies. I am mainly interested in improving my results on granite and marble and just had a thought about the topic. I have used Photograv in the past but I have about come to the conclusion that the dithering in the Epilog driver does just as well with the proper settings. I have a new shipment of granite and marble plaques coming in next week and intend to produce some new sales samples. I'll post my results asap.

Duane Parcells
05-30-2010, 11:04 AM
Both of these are on LaserTile. The source was a scan of a 25 year old 4by4 picture. This is one of 4 6" tiles. The epdithstd is the prepared photo sent to the epilog driver. It was set to standard dithering. The phtgrv file is the same picture processed with Photograv set to the Generic Laser Tile setting. It too was sent to the Epilog driver set to standard dithering. The phtgrv file looks muddy and dark areas look painted on. Only two examples but all I ran, once the photo is processed or dithered by whatever means the driver didn't make any difference I can see. Photograv did much better on wood than LaserTile.

James Jaragosky
05-30-2010, 11:28 AM
Both of these are on LaserTile. The source was a scan of a 25 year old 4by4 picture. This is one of 4 6" tiles. The epdithstd is the prepared photo sent to the epilog driver. It was set to standard dithering. The phtgrv file is the same picture processed with Photograv set to the Generic Laser Tile setting. It too was sent to the Epilog driver set to standard dithering. The phtgrv file looks muddy and dark areas look painted on. Only two examples but all I ran, once the photo is processed or dithered by whatever means the driver didn't make any difference I can see. Photograv did much better on wood than LaserTile.

I may be in the minority here but I like the photograv tile better. I think it is the enhanced contrast that makes me lean this way.

Dee Gallo
05-30-2010, 12:11 PM
I find that Lasertile requires a more severe contrast treatment because you will not get a good black from it no matter what you do. Dark grey is the best you can ask for, so you have to bump up the contrast.

Using Cermark for tile, your prep can be more like what you would use on wood or even acrylic.

my 2 cents worth of experience, dee

Dan Hintz
05-30-2010, 12:44 PM
I may be in the minority here but I like the photograv tile better. I think it is the enhanced contrast that makes me lean this way.
I'll add to your supposed minority, then... the PG file looks significantly better. The image on the right has too low of an lpi setting (probably under 100 lpi), making it look too much like a newspaper printing. Because of the higher lpi setting with the PG image, the detail in the image looks sharper.

I'm not saying PG is necessary, as I know it's not, but something nasty happened to make the image on the right look pretty bad.

Rodne Gold
05-30-2010, 1:11 PM
I also think the PG file is a lot better - the other , as Dan says , looks like a low res newspaper print

Larry Bratton
05-30-2010, 2:01 PM
Yes, I like the PS result better. The other one looks like a halftone or something.

Tim Bateson
05-30-2010, 11:48 PM
This may be a stupid question but I'll chance it.
When raster engraving with the Epilog driver, the default is Standard Dithering. If one has used a program such as Photograv to dither a photo or other prior to printing, would the additional dithering applied by the Epilog driver have an adverse effect on the engraving? Just seems redundant to me. Does Photograv compensate for this?
I'm still scratching my head trying to figure out why on earth you would even bother with PhotoGrav??? The Epilog Dithering works fantastic. Just experiment a bit & you'll get a good feel for when to use Standard -vs- Lighten -vs- Jarvis etc... I use most of them, but in my tests I have to admit that I found very little difference between Jarvis and Floyd Steinburg. I'm sure there is a difference, but I have not been able to discern any.

Rodne Gold
05-31-2010, 2:08 AM
Pgrav doesnt just dither - it does other stuff like edge enhance etc - you can do all that prior to sending the file to the laser in other editing packages as well - search for "the gold method" ...PG is just an easier way that takes your lasers characteristics and the materials properties into the mix. I actually hardly use it for photos and more for vector clipart as it stops all problems with vector fades , wrong colours for your laser driver and hidden vector lines.

Tim Bateson
05-31-2010, 12:23 PM
Pgrav doesnt just dither - it does other stuff like edge enhance etc - you can do all that prior to sending the file to the laser in other editing packages as well - search for "the gold method" ...PG is just an easier way that takes your lasers characteristics and the materials properties into the mix. I actually hardly use it for photos and more for vector clipart as it stops all problems with vector fades , wrong colours for your laser driver and hidden vector lines.
This is the 1st time since I've been on this forum that I've heard a good use for PG. I've never thought to try ClipArt. Thanks Rodne, I'll have to check that out.

Larry Bratton
05-31-2010, 4:24 PM
I'm still scratching my head trying to figure out why on earth you would even bother with PhotoGrav??? The Epilog Dithering works fantastic. Just experiment a bit & you'll get a good feel for when to use Standard -vs- Lighten -vs- Jarvis etc... I use most of them, but in my tests I have to admit that I found very little difference between Jarvis and Floyd Steinburg. I'm sure there is a difference, but I have not been able to discern any.
Just dumb I guess Tim. Paid $300 bucks or so for it back when and just keep on trying to justify my investment..sighhhh.

Frank Corker
05-31-2010, 7:26 PM
From the two images above. The photograv one looks better because of the level of contrasting. You can do that to the other image before sending it to the laser, by sharpening and adjusting the tones. The differences are much as I said in my earlier post. Photograv is extremely fast at making the adjustments. The Gold Method is also extremely fast, in fact quicker than Photograv.

The Epilog's image is definitely halftoned, but it is quck without the need to do anything as can be shown above, on glass I suspect it would be the clearer of all the images because the half toning is 'even' throughout. PG and TGM both use the sharpening features to enhance the image and they will as a result, be more harsh. Halftoning is even throughout, around the edges, on the eyes the features and why it appears to be softer. On a large image I think it would be the one that stands out.

Personal preferences though.