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Darren Null
08-30-2007, 7:18 PM
...by CorelDraw. Still.

Alternative posts title "Leggo my ears- I know what I'm doing", the oft-shouted cry of a female ex-workmate web designer when MS Frontpage used to inject loads of MS junk into her hand crafted code- it became a bit of a catchphrase.

So. I've found the laser driver's bit that's automatically dithering (badly) images and I'm now running in full manual mode so the laser driver in theory just passes the info to the laser.

But CorelDraw is interfering with my lovingly-crafted 1-bit images (that I make in Photoshop because I can work that and because much of the imagery is taken straight from my camera and requires a bit of fluffing and boiling down to essentials first). But CorelDraw still does things to the image.

No matter how big the image is, or how far I shrink it, I get the error message Part of your image is below 96 DPI. I bloody well know it isn't. As far as I know the workspace is 300 dpi, as the default DPI of my laser, (thanks to Rodne and this thread:
http://www.sawmillcreek.org/showthread.php?t=64425

I've even, with micrometers, made images that dot-for-dot were EXACTLY the size I needed for the job and CorelDraw messes it up; gives me the "96 DPI" error and passes out substandard cack.

The only way I can lose the "96 DPI" stuff is use the "convert to bitmap" command, which does equally unwanted stuff to the image.

How can I get CorelDraw to do my bidding or -better yet- leave my images alone?

Scott Shepherd
08-30-2007, 7:23 PM
Why don't you print it from Photoshop?

Darren Null
08-30-2007, 7:29 PM
My laser won't talk to photoshop for some reason. The print file disappears into the ether.

Bill Cunningham
08-30-2007, 9:39 PM
If your getting that message, someplace in the file your sending to the laser is a low res. bitmap.. You can set everything in corel, and the laser to 300 dpi or more, if the bitmap in your file is low res your not going to get high res from it and corel is warning you about it..
Click on your bitmap, and then click the bitmaps command on the top.. When the drop down menu comes down click 'resample' then look at the Resolution.. I'll bet it less than 96 dpi.. If it is, there is nothing you can do to increase the quality.. Sure, you can increase the resolution to 300 in the resample, but all your going to get is a 300 dpi depiction of a low res image and the error message will be gone, but your still going to get a crappy engraving. what you see on your screen (which is about 96dpi) is 'nothing' like what you will get with a device that expects to render at 300 dpi.. When someone sends me something to engrave or etch, I always ask them to send it 4 times bigger than they want it to be engraved becuse I 'know' I'm going to get a 75 dpi low res .jpg or something like that, once I resize it to 300 dpi, it shrinks by 4 and I get 300 dpi at the final size I want.. This isn't the best way to do it, but it's certainly quicker than trying to explain to the customer that the perfect image of that piece of web clip art the screen shows, is a lie :rolleyes:

Stephen Beckham
08-30-2007, 9:56 PM
Darren,

The other thing that I have seen that causes this error is 'ghosts.' Lack of better terms of course. It can be as small as a few pixels that are still in the image but less than the desired 96 DPI. May not be your main object that you are focused on, but something is hiding in there...

If you have all your image coverted up to 300 DPI and still get the error, there is something still hiding.

Double click on the PICK tool and it will select everthing in your working document. Once you have everything selected - look for the small squares that identify different objects.

You have a couple choices - sort through and find the ghost and up convert it or remove it if it's not part of your target (remember it can be behind an object) - use COMBINE or WELD or other function to see if it will show it - right click a loud color to outline everthing - click and drag to see if outlines show up. All of these will require an UNDO to fix what ever happens.

The last option is to CONVERT TO BITMAP. Since you have everthing selected - when you convert it all to a bitmap, it will combine it just as you see it. If you convert it to a 300 DPI it should work. This option may cause fonts to blur on the edges from smoothing.

In any case - I use UNDO/REDO several times to look for any slight changes. If you get all the strays out this way, you should no longer get the error...:)

Dave Jones
08-31-2007, 9:09 AM
Before you save your image from Photoshop, go to Image > Image Resize. Uncheck the "Resample" checkbox and then change the dpi to 300. Now save it. This won't change the number of pixels of the image, but just sets the dpi of the image to a higher number.

Adam Stacey
08-31-2007, 9:20 AM
What laser do you have?

Darren Null
08-31-2007, 11:16 AM
Thanks for your suggestions, but none appear to be doing it for me. I have labelled images 300dpi in photoshop, but they appear as 72dpi when imported into corel. When I squish them down to the intended size, the scale and DPI readouts seem to be telling me the truth (100% scale comes out as 296dpi which is close enough for government work) AND YET- when I come to print it "Image under 96 DPI". This applies even to a 6000 pixel image that I'm putting onto 1cm square. I KNOW it's not under 96 dpi, but coreldraw insists it is, and when I go to print, the quality would seem to indicate that the image was under 96 dpi even though it definitely wasn't.
http://cambs.com/etch/printerference.gif
I've prepared a demonstration screenshot to illustrate the problem. The only element on the page is the rose bitmap- 300 dpi, 8.67cm across (or 1024 pixels if you prefer things that way). It's been squished down to an apparent 720dpi, and I'm still getting the "image below 96dpi" message. NO IT'S NOT!!!!!!

NOTES: The "output doesn't fit on media" is there so I could fit the image on the screenshot under the error message, so it wasn't properly on the paper. It looks a little scruffy because I saved 40Kb by saving the screenshot as a gif.

I have been caught out by 'ghosts' before now, but that isn't the case this time.

My laser is a GCC Mercury. The laser driver is set at 300dpi for the default value

George Elston
09-01-2007, 8:08 AM
I was able to recreate your error when I imported a JPEG into coreldraw. Try saving your picture as a TIF. Different raster (photo) file formats are codded differently. Usually the first line in the file states the resolution and the size, so the application knows that the first line of pixels is x number of pixels long and then the next row of pixels starts. JPEGS are different in that they are loosey (that is compressed) and by default 72 dpi, so it really doesn't matter what you tell it in photoshop, many apps will see JPEGS as 72dpi no matter what you do. You could try saving with eps encoding or some other tricks but why? Just save as TIFF.

Darren Null
09-01-2007, 10:18 AM
Thank you George. JPEG is what's doing it. I've been doing web-style graphics for so long now that it just didn't occur to me to use anything else. Plus that's what comes off my camera, which is my main source of clipart (not even a hint of copyright problems that way!).

Oddly enough, earlier versions of CorelDraw handled JPEG fine, and it started doing this around version 10; which is when (and why) I stopped using Coreldraw. It's not only the irritating error message- from the look of prints, it must print at 72dpi at the size you have the image in the layout; however many pixels are crammed in there. I assumed it was some environment setting that I couldn't find, and I spent a lot of time on google trying to find it before giving up and just doing layouts in photoshop (more labour intensive but much better end quality).

I also assumed -wrongly- that if I just got the right number of pixels in there that CorelDraw would cope with things. *sigh*

Thanks very much. TIFF. Sorted.

George Elston
09-01-2007, 11:50 AM
I was pretty sure that was the problem. Glad to hear I was right. JPEGs can cause other problems also, and while I'm on this soapbox---. JPEG is a great file format for web work and has become the defacto format for digital cameras, BUT JPEG is an algorithm that makes decisions about the color in the photo and I don't like the computer making decisions for me. If you open up even your "High-Res" JPEG pictures from your camera in Photoshop and look at the red, green, or blue channel alone, (zoom in to 200%) you will see big squares, where the JPEG has decided that it can "average" the colors and the human eye will never know the difference. It's true, but an imaging device, like a laser, can see the difference and when it images these "blocks", the human eye can see the difference also. Especially since most lasers only really image 4bit (16 levels of grey). Try saving a JPEG with a higher compression ratio and do the same thing with the channels, the "Blocks" have gotten bigger and more discern able. If at all possible, for high quality work I like to work in TIF, even if you use LZW compression it is a "LossLess" algorithm. However, once a photo has been a jpeg it doesn't make any difference what you save it as, the image quality loss is always there. You can't make a cucumber out of a pickle, no matter how hard you try. I have seen people pulling their hair out over "artifacts" in their etched image that were caused by JPEG compression, and not by a bad laser.
So, were stuck with JPEG, but we need to be aware of it's limitations, and realize that it can cause all kinds of problems that are inherent in the file format and not a problem with the laser or drivers.

Just my 2 cents worth

Darren Null
09-01-2007, 12:18 PM
For the record, CorelDraw doesn't like PNG files either (lossless web format with variable transparency- good for drop shadows on multiple coloured backgrounds).
EDIT: YAY! PSDs (photoshop's native format) work!