question with photo engaving

[Scott Shepherd]

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]

Thanks Guys, that makes perfect sense now. I have been fooling with photo's long enough and should have known that.

Bruce

[Chuck Stone]

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]

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]

Here is a pretty good link on the subject http://www.espressographics.com/text/imagesize.html

[Scott Shepherd]

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]

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]

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]

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]

Guess I shoudl have checked for page 2 before posting... Steve took care of the explanation for me

[Martin Boekers]

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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]

So I will let others explain it better...

Yep - it is a whole book!

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

[Dan Hintz]

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]

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?

[Dan Hintz]

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

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