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Chad Fitzgerald
01-20-2013, 12:31 PM
i convert my photos to b&w stucci, either 250 or 380 dpi depending on the material.
ive been getting verticle lines(has the appearance the laser missed) evenly spaced. seems to be most noticable oin the 380 dpi.
the lines are somewhat faint, but noticable. problem is it isnt on every pic.
i often use photos with low dpi to start and increase dpi, also i sometimes enlarge them.
would either of these be the issue. could it be how stucci converts it?
tried taking pics but yet to be able to get a photo to show it. i can keep trying if necessary.
thanks
chad
here is a pic dont know if you can see it
251841

Richard Rumancik
01-20-2013, 3:47 PM
Chad - Are you certain that you are plotting at the same resolution as the photo? ie make sure you have the laser set to 380 if that is the photo resolution.

Upscaling a photo is not the best thing to do. I understand sometimes you have no choice. Better to ask for a better photo when possible. You might need to research the topic or upscaling and get some ideas. I saw some info on a PhotoShop tutorial where they upscaled 5 or 10% at a time and did this a few times - apparently to reduce artifacts etc. I'm no expert on this . . .

I can see a faint white vertical line starting at about the 7:30 position. I doubt it is a problem with using Stuki. Is your source a jpg? If so make sure you turn off all compression while working on the file - or convert it to a tif before you even start any edits and resampling.

One thing you might try - rotate the existing bitmap file 90 degrees and plot to see if the line rotates. If it does I'd say the file has an artifact from a process run on it. If it is still vertical then I'd think it is banding - the cause of which could be many things, including hardware such as bearings. Maybe do a search on this forum on "banding" and see what comes up.

Larry Bratton
01-20-2013, 3:50 PM
Chad,
You say you convert them to 250 or 380 etc. What resolution are you starting out with? The photo needs to be of sufficient resolution to start with, you can't just take a 72dpi photo and change the resolution and expect that to work, it won't. Even if you have a decent photo you need to use proper software and procedure to make those changes.

Ross Moshinsky
01-20-2013, 4:17 PM
I really don't think people understand DPI. DPI doesn't exist on computers. DPI is just a conversion/scaling factor for resolution.

Taking a 10"x10" 72dpi image and shrinking it to 5"x5" makes it a 144dpi image. It's exactly the same thing. People get way too caught up in DPI with lasers. DPI becomes very important in large format printing because you need that extra information. On a 3"x3" image, DPI is relatively insignificant. The quality of the image is far more important.

Martin Boekers
01-20-2013, 4:33 PM
I can't tell you how many times someone sends me a screen shot (72dpi) and says it looks great on my computer......

So yes DPI does matter! Yes you can "res" up an image by "resampling" at a higher DPI, and it will help, it won't make it
a great image but it will help. You can have a nice quality image that will not look good at it's engraved or printed resolution
so It's hard to say that quality alone will make it better. Chances of "banding" or creating "artifacts" are definitely greater if the
image is not the same resolution or a direct multiple of it. If you want to do a test, take an image and laser at 3 different resolutions,
then you should see the difference. Take the above example. I think you will see a difference if you engrave a piece 10x10 at 72 DPI
an one at 5x5 at 144 DPI, there will be a visible difference. Now, if you want to talk "viewing distance that is a whole different discussion...

Ross Moshinsky
01-20-2013, 5:14 PM
I can't tell you how many times someone sends me a screen shot (72dpi) and says it looks great on my computer......

So yes DPI does matter! Yes you can "res" up an image by "resampling" at a higher DPI, and it will help, it won't make it
a great image but it will help. You can have a nice quality image that will not look good at it's engraved or printed resolution
so It's hard to say that quality alone will make it better. Chances of "banding" or creating "artifacts" are definitely greater if the
image is not the same resolution or a direct multiple of it. If you want to do a test, take an image and laser at 3 different resolutions,
then you should see the difference. Take the above example. I think you will see a difference if you engrave a piece 10x10 at 72 DPI
an one at 5x5 at 144 DPI, there will be a visible difference. Now, if you want to talk "viewing distance that is a whole different discussion...

Low quality and low DPI are not the same thing. Computers don't know DPI. Computers know resolution. DPI is just a piece of information stored in the file to provide a scaling factor. There are no "dots" on a computer screen or in a digital file. There are only pixels. When you "res up" an image, you're increasing the resolution of the image. You're not changing the DPI. DPI is just a way to express the difference between digital media and "printed" media.

Martin Boekers
01-20-2013, 6:21 PM
Low quality and low DPI are not the same thing. Computers don't know DPI. Computers know resolution. DPI is just a piece of information stored in the file to provide a scaling factor. There are no "dots" on a computer screen or in a digital file. There are only pixels. When you "res up" an image, you're increasing the resolution of the image. You're not changing the DPI. DPI is just a way to express the difference between digital media and "printed" media.

I guess it my photo background kicking in, but yes, you can have a poor quality image, out of focus, bad exposure etc.
and giving it more information (Pixels Per Inch) may not help it. I do understand that computers use pixels and not dots
per say. I see when I resize an image in PS I have a choice to resample or not. If I choose not with 10x10 at 72PPI and change it to 5x5 the PPI becomes 144, now when I tell PS I want to resample 10x10 at 144PPI it interpolates the 10x10 and
at that size there is now more information in the file. My Epilog fires dots and I set it for what DPI I need. The less DPI I
engrave at, the less information the file is engraved at. So yes we can discuss terminology.
In the printing industry Dots or in some case shapes where burned to films, pretty much standard. The one thing I don't believe has changed is that the more information that is in an inch, be it pixels or dots the more information will be included
in the engraving if set properly in the print driver. If I have an image say 5x5 at 72PPI and print it at 300 it would visibly less
quality than if I started with an original image that was 5x5 at 300PPI. The thing I suggest is find a standard quality size that works for you, One of the first things I do for new employees is have them do a series of tests, First is text, I have them engrave it at 150, 300, & 600 DPI (Epilog) so they can see the difference, then I have a file with an image and do the same thing, the final being a 3 copies of the same image shot at hi, med, and low resolution, They engrave all 3 at 600DPI so they can
see the difference. It's easier to see then to have a non graphics person understand the concepts. The next stage is understanding compression and what happens as you save a file over and over as it loses some of its detail through interpolation. All this is why engravers should get graphic education along the way to understand how to optimize their work.

Michael Hunter
01-20-2013, 6:22 PM
Some of these threads are getting far too technical to be of help to the posters of the original questions.

Martin's comments may not be technically correct, but it is the case that most computer users seem to use the terms dpi and ppi interchangeably and most (including me) will understand EXACTLY what he is on about.

Similarly, in the thread about lenses, the original poster (who apparently did not really understand much about lenses at all) has now been presented with drawings which, while technically correct, cannot be properly explained without getting deep into the maths and physics of the properties of lenses.

Whilst not condoning incorrect answers in any way, it should be possible to answer questions in a way understandable to the original poster and this may mean using a simpler "models" to explain things or using terms like dpi in their "everyday" usage.

Chad Fitzgerald
01-20-2013, 6:27 PM
for this photo, came off FB, came in at 72, changed to 380. i had run this same photo pn tile with no issues. this time(begining from original) on changed to 380, increased size, and got the verticle lines.(you can barely see one just to the right of her ear.
how do i turn off compression??
sounds like maybe if im making the image larger, this may be doing it.
i do believe its something in my process causing it, not the laser, simply because only happens with some photos. And any time it does happen, the vert lines are spaced perfectly across the pic. 7/8" gap in this one.
i also understand the 72dpi pics are not ideal. i use these when practicing new stuff, with friends and family pics. I guess im trying to figure out what causes it in order to avoid problems on real jobs.
here is what i do
import pic, crop pic, resample to either 250 or 380 dpi and change size as needed.
adjust image brightness, etc, convert to BW stukki.
thanks for the help

Michael Hunter
01-20-2013, 6:56 PM
import pic, crop pic, resample to either 250 or 380 dpi and change size as needed.


Try doing the RESAMPLE step LAST. I think that that may solve your problem.
If you alter the size after resampling, you loose the relationship between the picture resolution and the dpi set on the laser.

Dee Gallo
01-20-2013, 8:38 PM
Try doing the RESAMPLE step LAST. I think that that may solve your problem.
If you alter the size after resampling, you loose the relationship between the picture resolution and the dpi set on the laser.

I agree with Michael. I'm no expert, but I always start with the photo at the correct size before playing with it. Seems to work for me.

Bruce Dorworth
01-21-2013, 12:20 AM
I am not sure I understand this process. Every picture that I take with my digital camera comes up at 72 dpi. Does that mean that you have to use it at 72 dpi or can you resample this image?

Bruce

Mike Null
01-21-2013, 6:50 AM
Bruce

Your camera should have a range of resolution options.

Dan Hintz
01-21-2013, 7:14 AM
I am not sure I understand this process. Every picture that I take with my digital camera comes up at 72 dpi. Does that mean that you have to use it at 72 dpi or can you resample this image?

Bruce
This is merely an artifact of desktop publishing programs... ignore the dpi value attached to the image. Simply look at the area you have to work with and make sure the resoltuon of your image fits that area when printed at the resolution you want. For example, if you have a 2"x3" area that you wish to print at 300dpi, your image should be 600x900 pixels.

Mike Null
01-21-2013, 8:20 AM
Dan

Do you want to elaborate on that? My camera resolution is what I get when I download the images to my computer. That resolution remains until I choose to alter it with PhotoPaint.

Scott Shepherd
01-21-2013, 8:45 AM
Monitors display at 72 dpi, historically (it's 96 or something now), but let's just say 72 dpi is the resolution a monitor displays at. Printing requires 300 dpi for normal photo printing. Your image file has a resolution and a size. It might say it's 72 dpi and the size is 3624 x 2448 (pixels). You divide the pixels by the resolution and you'll have your print size. For example, if you printed this at 72 dpi, then you could print a photo that was 50.333" x 34" in size. However, if you wanted a quality photo, at 300 dpi, then this same photo at 300 dpi would be 12.08" x 8.16". You simply divide the pixel dimension by the resolution and you'll have the size you can engrave it at.

If you plan to engrave something at 250 dpi, then you need to size it correctly so the math works out. You can skip that step if you want, but these mismatches in the math, I believe, are what cause many of the minor problems that people can't solve. Your photo should match your output. If you put a 300 dpi image in and you're engraving at 250 dpi, then the software has to figure "something" out. It's that "something" that I believe causes very fine, minor issues. When they match, you take that one thing out of the equation, and then all the problem solving can shift somewhere else.

Just my opinion on it.

Bruce Dorworth
01-21-2013, 12:03 PM
Thanks Guys, that makes perfect sense now. I have been fooling with photo's long enough and should have known that.

Bruce

Chuck Stone
01-21-2013, 12:32 PM
Thanks Guys, that makes perfect sense now. I have been fooling with photo's long enough and should have known that.

Bruce

Good reminder that answers aren't here just for the person asking the question.

Chad Fitzgerald
01-21-2013, 12:53 PM
thanks scott, thats starting to make sense to me. up til now im simply editing bitmap, changeing size to what i want and dpi to what i engrave at. sounds like this make be causing my problem. sometimes it works other time i get the vert. lines.
Do you mind sharing the proper way i should do this? for example,
customer wants a photo engraved on a 6x6 tile. customere send a picture, lets sy its the example you used, 72dpi, 3624x2448 pixels. Obviously we want to fill the space best we can. for me i use 380 dpi for tiles. but that photo then is 9.53 x 6.44 ". Too big for the tile. need to make is smaller.
Can you explain the best way to do that. also how to make bigger if its not the same.
thanks
chad

Larry Bratton
01-21-2013, 6:19 PM
Here is a pretty good link on the subject http://www.espressographics.com/text/imagesize.html

Scott Shepherd
01-21-2013, 6:41 PM
thanks scott, thats starting to make sense to me. up til now im simply editing bitmap, changeing size to what i want and dpi to what i engrave at. sounds like this make be causing my problem. sometimes it works other time i get the vert. lines.
Do you mind sharing the proper way i should do this? for example,
customer wants a photo engraved on a 6x6 tile. customere send a picture, lets sy its the example you used, 72dpi, 3624x2448 pixels. Obviously we want to fill the space best we can. for me i use 380 dpi for tiles. but that photo then is 9.53 x 6.44 ". Too big for the tile. need to make is smaller.
Can you explain the best way to do that. also how to make bigger if its not the same.
thanks
chad

That's a little tricky, since it's a rectangular photo and a square piece. Normally, I'd crop it to a square before I start, but in this case, we'll just let it bleed over the edges. Let's assume you want to fill the tile, top to bottom and let the left and right edges go off the edges. The height is currently 2448 pixels. You want 6" tall at 380 dpi. So resize it to 2,280 pixels on the height and let the width end up wherever it ends up. That'll give you a 6" tall image at 380 dpi. Import that into Corel as whatever you want (TIFF works decent) and then just engrave it at 380 dpi.

Then your engraving matches your photo. I'm not suggesting this is some magical "fix all" for issues, but once I started doing this, it seriously helped the quality of my photo engraving in several areas. A lot of the little issues went away, and it also allowed me to try a variety of things to see if they mattered at all. I spent several hours one day, engraving the same photo on a bunch of scrap acrylic I had left from a job and documenting the results. Things you'd think would make a difference, made no difference at all. There wasn't much difference in a lot of settings. I also found I could engrave at a much lower resolution than I previously thought and get really good results.

Ross Moshinsky
01-21-2013, 8:58 PM
Open a new Photoshop/Photopaint file. Setup your size and DPI.

Import your image into into Photoshop/Photopaint.

Scale/Crop it as necessary. (Note: Try to always scale down, not up. If you need the image larger, you try to find a happy medium between dropping the DPI of the blank file and increasing the resolution of the desired photo).

Convert your photo to a "laserable" format via your chosen method. Save as a 1 bit BMP.

If your file is 300dpi, engrave at 300dpi.

Dan Hintz
01-22-2013, 8:13 AM
This topic comes up about once a year. The resolution of the image is fixed and is based upon the imaging element within the camera... for example, my Canon T2i takes 18Mpixel images. The (max) resolution is fixed at 5,184 x 3,456 pixels. The resolution of the image never changes. If I print it on a 17.3" x 11.5" page at 300dpi, the image is still 5,184 x 3,456 pixels. The same holds true if I print the image on a 8.6" x 5.8" page at 600 dpi... the image is still 5,184 x 3,456 pixels.

When you open that image in your paint program, it likely says 72dpi, but that does not mean there are any more (or less) pixels in the image. The size of the final printed image is determined by how many pixels you have vs. the dpi you choose to print at.

Scott Shepherd
01-22-2013, 8:18 AM
I might also add that I have found problems can creep in by using various adjustment tools, like dodge and burn. I used those tools in one of my test a great deal and what looked great on the screen (even at 100% size), ended up with some odd banding. The photo before it, where the adjustment was not done and everything else was processed the same, except with no dodge or burn used, did not have those issues. I saw this in several editing tools. So just be aware that some things are going on at that level that can cause issues too.

Dan Hintz
01-22-2013, 8:30 AM
Guess I shoudl have checked for page 2 before posting... Steve took care of the explanation for me ;)

Martin Boekers
01-22-2013, 9:51 AM
.


Whilst not condoning incorrect answers in any way, it should be possible to answer questions in a way understandable to the original poster and this may mean using a simpler "models" to explain things or using terms like dpi in their "everyday" usage.

Some things such as resolution, compression, sizing and color management sometimes aren't easy to explain as can be seen here...
Many of us have an understanding of the concepts and the problems that can occur along the way. Sometimes it's not easy to put into
terms for those working with graphics for a short time. I finally quit trying to get clients to understand why a 72 (DPI/PPI) image looks great
on the moniter, but looks like %$#@ when printed...So I will let others explain it better...

Michael Hunter
01-22-2013, 12:30 PM
So I will let others explain it better...


Yep - it is a whole book!

WHAT HAPPENED TO DAN'S BOOK ????????

Dan Hintz
01-22-2013, 1:53 PM
WHAT HAPPENED TO DAN'S BOOK ????????

Quality material takes a long time to write (and a lot of research / testing is involved, too... I'm not just jotting my thoughts down on paper, I want it to be factually correct). It's a lot of material. It's likely you'll all be experts before the book is in print ;)

Scott Shepherd
01-22-2013, 2:27 PM
Quality material takes a long time to write (and a lot of research / testing is involved, too... I'm not just jotting my thoughts down on paper, I want it to be factually correct). It's a lot of material. It's likely you'll all be experts before the book is in print ;)

So it's going to be like releasing a Windows 3.0 book when the world is using Windows 8? :p

Dan Hintz
01-22-2013, 5:00 PM
So it's going to be like releasing a Windows 3.0 book when the world is using Windows 8? :p

Unless we move to quantum dot lasers in the meantime, consider more like Windows 8 on a Windows 7 book :p