heavy pixilation in photgrav

[Craig Hogarth]

using older version of photograv, i've been having some problems of late with big dot sizes. settings are set to 333dpi, .005 inch beam (2in lense) and my laser specs are correct. The problems are with every photo, editted or not.

any ideas? They're coming out pretty bad and nothing has helped.

[Jim Watkins]

I have pretty good luck when I export out from Corel at 300dpi, then when engraving, use the same 300dpi setting. I was always told to use the 300 by my rep.

BTW, just asking, but did you resize or rotate the image after processing? I have not done it, but the guys usually say that will kill your image. If you have, try exporting it in it's final size then processing it.

My mini24 uses a 2" lens with .004" beam and the ones I just got done doing today looked really good.

Good luck

[Craig Hogarth]

I don't do anything to the image once it's been processed. I'm doing it the same as I've always been. i even tried doing a picture that worked good in the past and I'm getting same pixilated results.....

[Tom Cullen]

I would on occasion get the same result as you have, grainy images. What I found helped a lot was this; Once I have the image open in say Photoshop, I would size the image to what ever size I needed for Corel draw then save it. Close the image completely and re open to set the DPI to whatever you need ( I usually set mine @ 300 DPI for images) once again save and close completely. By saving and closing in two steps this seems to help prevent grain. Not sure why this works , but It really solved my problems. I know you've heard this before but , make sure what ever size you set the image at in Photoshop ( or what ever application you use to edit ) that it stays the same size in Photograv ( and DPI should remain the same ) and also remains the same in Corel Draw.

Hope this is some help

Tom

[Craig Hogarth]

thanks tom. It didn't help, but it gave me an idea. I ended up resampling everything to 300 before exporting. I never had to do it before, but for now it seems to do the trick.

[Larry Bratton]

using older version of photograv, i've been having some problems of late with big dot sizes. settings are set to 333dpi, .005 inch beam (2in lense) and my laser specs are correct. The problems are with every photo, editted or not.

any ideas? They're coming out pretty bad and nothing has helped.
Craig:
What resolution are the images you are starting with? If you start with a low resolution image, then your not going to get the best results regardless of what you do, especially if your attempting to make them larger. Photoshop does a good job of resizing up to a point. Anyway, I try and get my bitmap images in as high as I can get them and then "res" them up in PS3 to 300ppi. This is the resolution that Photgrav uses as a minimum for good quality. Process at that, import the saved image into Corel. Do not resize or rotate. Then engrave at either 300 or 600. I find that 300 gives good results most of the time. I rarely raster anything above that. I've tried 600 a few times but it looks close to the same as far as I can percieve.

[Ed Newbold]

All of this is interesting, but so foreign to me. I tried using Photograv 3 tonight to process an image for burning into the back of a mirror. First thing was - this new expensive version doesn't list MIRROR as one of the materials, so I tried a wide variety of other materials with less tha acceptable results.

Now I'm hearing that once you get the "processed" image out of Photograv, you're not supposed to resize it.

Hmmm... when I import this image into Corel, it spreads over the entire 18x24 page. I need it sized down to a 5" width, but if what I'm reading is correct, this won't work. So, using Corel Photopaint, how does one "resample" to get it down to a 5" size?

Sorry if all this sounds so dumb to you, but we're here to learn from each other.

Thanks very much.


thanks tom. It didn't help, but it gave me an idea. I ended up resampling everything to 300 before exporting. I never had to do it before, but for now it seems to do the trick.

[Larry Bratton]

All of this is interesting, but so foreign to me. I tried using Photograv 3 tonight to process an image for burning into the back of a mirror. First thing was - this new expensive version doesn't list MIRROR as one of the materials, so I tried a wide variety of other materials with less tha acceptable results.

Now I'm hearing that once you get the "processed" image out of Photograv, you're not supposed to resize it.

Hmmm... when I import this image into Corel, it spreads over the entire 18x24 page. I need it sized down to a 5" width, but if what I'm reading is correct, this won't work. So, using Corel Photopaint, how does one "resample" to get it down to a 5" size?

Sorry if all this sounds so dumb to you, but we're here to learn from each other.

Thanks very much.
Ed:
In Photograv 3.0 use the Resize Image feature. It also needs to be 300dpi. (Photograv suggests 150dpi and engrave at 300) Try both and see which you like.
I assume you are speaking of glass mirror and not acrylic. I don't do mirrors but I assume you use glass as the material selection. If your enraving on the back, reverse the image so that it's oriented correctly. On regular glass, the background needs to be black before it comes into Photograv. Read the glass engraving tips under the Help menu. I'm sure someone here can give better advice on engraving mirror than me. I have been intending to try it but haven't gotten around to it. I used to sandblast them and that was pretty cool. Good luck!

[Ed Newbold]

Ed:
In Photograv 3.0 use the Resize Image feature. It also needs to be 300dpi. (Photograv suggests 150dpi and engrave at 300) Try both and see which you like.
I assume you are speaking of glass mirror and not acrylic. I don't do mirrors but I assume you use glass as the material selection. If your enraving on the back, reverse the image so that it's oriented correctly. On regular glass, the background needs to be black before it comes into Photograv. Read the glass engraving tips under the Help menu. I'm sure someone here can give better advice on engraving mirror than me. I have been intending to try it but haven't gotten around to it. I used to sandblast them and that was pretty cool. Good luck!
Thanks for the advice. I'll keep chipping away at this until I get it right.
Cheers,

[Bill Cunningham]

I use the old photograv, and do a number of mirrors..
Make sure your original is 300 dpi grayscale, sized to the size you need it, because you can't resize a binary image without a sometimes huge loss in quality. Then, process at 300 dpi using the 'cherry' wood setting. You can use interactive to flip the image (because your engraving from the back), or flip it in coreldraw by selecting the mirror image command. I usually run mirrors twice, could be it's just the mirror I get, but twice makes a huge difference in the quality of the detail engraved... If your original image is only a web photo at 75 dpi or so, re-sampling it to 300 will not improve anything.. Garbage in, Garbage out..

[Ed Newbold]

I'm trying to get it, but my issue seems to be this 300 dpi thing. I take a photo with my camera, and then when I download and save it to my computer, its original parameters are:

2848 x 2144 Pixels (6.11 MPixels)
72 dpi
39.6 x 29.8 inches in physical size

So, I "resample" it to 300 dpi and the parameters are now:

2848 x 2144 Pixels (6.11 MPixels)
300 dpi
9.5 x 7.1 inches in physical size

Therefore, changing it to 300 dpi resolution has reduced it physically in size. Thus, I assume that one must continue INCREASING the dpi to REDUCE the physical size you want it to engrave to... correct?

Thanks for your thoughts,


I use the old photograv, and do a number of mirrors..
Make sure your original is 300 dpi grayscale, sized to the size you need it, because you can't resize a binary image without a sometimes huge loss in quality. Then, process at 300 dpi using the 'cherry' wood setting. You can use interactive to flip the image (because your engraving from the back), or flip it in coreldraw by selecting the mirror image command. I usually run mirrors twice, could be it's just the mirror I get, but twice makes a huge difference in the quality of the detail engraved... If your original image is only a web photo at 75 dpi or so, re-sampling it to 300 will not improve anything.. Garbage in, Garbage out..

[Larry Bratton]

Ed:
You have a setting wrong in your camera to begin with. Your making your photo at the smallest size 72dpi (that's for e-mail). Reset the camera to the largest image size. You can always sample down without loss of quality. What kind of camera do you have? All digital cameras will have a setting that allows changes to image size. It's like Bill and I said, you need to start with high resolution. What a computer screen sees is the number of pixels an image has. It doesn't care about the resolution. But for printers and engravers, they want high resolution images with lots of dots that don't have to be stretched or manipulated.

[Ed Newbold]

Oh... OK.

It's a Konica-Minolta digital, and I thought setting it for the "largest" pixel settings would do it. I'll have to go into the menu system and figure out where the dpi resolution settings are maintained!


Ed:
You have a setting wrong in your camera to begin with. Your making your photo at the smallest size 72dpi (that's for e-mail). Reset the camera to the largest image size. You can always sample down without loss of quality. What kind of camera do you have? All digital cameras will have a setting that allows changes to image size. It's like Bill and I said, you need to start with high resolution. What a computer screen sees is the number of pixels an image has. It doesn't care about the resolution. But for printers and engravers, they want high resolution images with lots of dots that don't have to be stretched or manipulated.


Thanks for your patience and help! Will get back with you a bit later after I get the camera set up correctly.

[Larry Bratton]

Ed:
Read this article. It will help you to understand this sticky stuff.
http://www.luminous-landscape.com/tutorials/understanding-series/und_resolution.shtml

[Ed Newbold]

Ed:
Read this article. It will help you to understand this sticky stuff.
http://www.luminous-landscape.com/tutorials/understanding-series/und_resolution.shtml


Thanks, will read it.

Here's the operational data on my Konica-Minolta camera. In the "Camera Modes" section there's a blurb about "Quality" settings, which is probably where I need to focus (no pun intended), although I don't find any references to DPI settings anywhere.

Thanks a million,

[Larry Bratton]

Thanks, will read it.

Here's the operational data on my Konica-Minolta camera. In the "Camera Modes" section there's a blurb about "Quality" settings, which is probably where I need to focus (no pun intended), although I don't find any references to DPI settings anywhere.

Thanks a million,
What model is it? I think Konica Minolta is out of the camera business now, but I'm sure the manuals and all are online at their site. Tell me the model and I'll try and help. The "Quality" settings are more than likely where this needs to be changed.

[Scott Shepherd]

72 is PPI, DPI is a printer setting. Every camera I have ever seen saves in 72 PPI. I have a fairly expensive digital SLR and it saves everything at 72 PPI at the highest setting. It really means nothing in the camera world. There are huge debates about the validity of that number all the time.

You are correct, just enter the final size you want and resample it at the 250 or 300DPI you want and it'll make it in the right format at the right size.

[Larry Bratton]

Scott:
Correct, technically. However, they are, albeit a mistake, used interchangably. The best setting to use to take digital photos is RAW if your camera supports it. I use Nikon cameras and they do.This is the uncompressed data and can be processed by Photoshop. The best file format to save in also is a TIFF, not JPG. JPG is a lossy file and everytime you resave it, you lose more data and quality. BMP is OK too but usually is a bigger file. If your using Photograv 2.1, your forced to use BMP.Another format that is not a lossy format is PNG. It allows a transparent background also that can be specified on the save. Photograv 3.0 will import TIFF,BMP,PNG and JPG but will not output the engraved file to JPG.
If you use Photoshop, when you resample and image for printing, you can let Photoshop determine the best ppi automatically based on the desired Document size (physical print size or engraving size). It rarely returns anything higher than 266ppi. Knowing I need 300 for Photograv though, I just put that in and use Bicubic method of resample.
This stuff can be very confusing to one that has not worked with it before. However, their are tons of good articles and experts on digital photography and printing on the internet.

[Ed Newbold]

Thanks, will read it.

Here's the operational data on my Konica-Minolta camera. In the "Camera Modes" section there's a blurb about "Quality" settings, which is probably where I need to focus (no pun intended), although I don't find any references to DPI settings anywhere.

Thanks a million, Opps, I forgot. Here's the link to my DiMage Z3:

http://www.imaging-resource.com/PRODS/KMZ3/Z3A.HTM#operation

[Larry Bratton]

Ed:
Looks like this camera saves at 72ppi. It also saves as JPG period. Your size options are 2272 x 1704 ppi as the largest and 640 x 480 as the smallest, and a couple of in between sizes. Quality options being Fine,Standard or Economy. Shoot at FINE. I would shoot it at something other than 2272 x 1704. Then take it to Corel and resample and size it.