View Full Version : Cleaning up low resolution jpg logos for rastering

john banks
03-19-2012, 10:53 AM
When you have a low resolution jpg logo (that looks monochrome but actually hides all sorts of gray on the jpg artefacts and antialiasing) that prints acceptably on an inexpensive laser printer because of the dithering quality achievable with the tiny size of spots of toner, and you then raster engrave the same logo with typical CO2 laser spot size, the results are often not acceptable to my eyes. If the customer cannot supply better quality artwork with vectors (or you cannot find a vector logo because of the esoteric logo), or higher resolution, without jpg artefacts and you are not commissioned to redo the entire artwork, and tracing just follows the artefacts, you look for a quick and dirty way to make it look decent to run the job, or you decline the job.

Given that the gray levels are transformed into an on or off by the laser, then it strikes me that with the available spot size, you really don't want to dither grays because it can produce feathered edges or effects that look like bad backlash adjustment. Whether you dither manually or with a script/macro, or your printer driver does it, I cannot imagine good results, but please say if you find otherwise.

The best method I've found so far is to adjust brightness and contrast before reducing to a 1 bit image without dithering (say just using a threshold).

I also find that the power/speed need to be carefully selected on many materials to match the density of the design, so more power for the same material for a design that has thin areas that are widespread, and less power if there is lots of detail or blocks of fill.

How does this work for you guys and what other techniques have you found useful? Do you agree or disagree with my opinion about the lower quality due to spot size or do some machines manage to take the same tricky image and have it look like a laser printer?

Martin Boekers
03-19-2012, 11:20 AM
You can try to "res up" the image that will help a bit, sometime you can do a slight Guassian blur.

You can fiddle with this and fiddle with that, but bottom line GIGO (garbage in- garbage out!)

WQhat you may want to do is to create a sample you can have on hand to show folks what
a bads image looks like engraved.

Some times I have to teach them a bit, They take a screen shot from a web page and think
it looks good on the computer screen and they don't understand that doesn't compare to
printed or engraved piece.

Steven Cox
03-19-2012, 11:33 AM
If a customer gives me a image I just tell em it will take 2 -3 hours to clean it up & can't gaurantee it will be OK, but I'd have to charge them for that time. 9 out of 10 times they amazingly come up with a better image.

There are tricks to bring up an image but it really depends on the image itself, without seeing it it's hard to say what's the best approach.

john banks
03-19-2012, 11:40 AM
Even before officially starting trading, whilst in our preparation phase, the early queries coming in from word of mouth and contacts (which is great) are showing that it is going to be one of the major themes that customer education is going to be never ending. Hardly anyone understands what makes a good image, and even after you explain it most still don't get it. I like your idea Steven of how to make it worth their while to get a better image, but I know that some customers will think you're trying to pull a fast one even though you're not.

It is surprising how decent even an unprepared picture can look on a cheap laser printer though. I hoped that asking someone to print it on their printer in monochrome would make the point, but it doesn't!

Martin Boekers
03-19-2012, 11:44 AM
There are a handful of tricks, I try not to spent too much time unless it's something I will use
on future orders quite a bit. I try my best to get a better image, as when the product goes
out with my name on it, it is too easy for others to critisize my efforts not knowing what I started
with. It can put my shop in an unfavorable light.

There are some fractal programs out there that will help.

One thing to consider is how you address the charges for graphic work, and who owns the efforts
you put out. Some call it file prep so there isn't the missunderstanding with the client about
whether you will provide a finished file to them or not. There have been discussions here both ways
about that. My preference is I retain the rights to the file I created that way they come back to me
instead of competion. Then again I don't typically charge for basic cleanups, part of what sets me
apart from competition.

Joe Hillmann
03-19-2012, 12:58 PM
I often do the convert to one bit line art then do a vector trace. If there are details that get missed that way then I do it again but raise or lower the thereshold and combine the best of the two images to get the detail I need.

Ross Moshinsky
03-19-2012, 1:48 PM
1. For 99% of the logos I convert to B&W. To get the power/speed right per substrate per logo is a waste of time. Most of the time you can get it to look right in a simple B&W format.

2. If a logo is in too low of a resolution, I google for a a better option. It's typically faster and more reliable then asking the customer.

3. Typically we vector trace in Inkscape and if necessary recreate the text manually. If the logo is a real pain and I think it will take more than 30 minutes, it's sent out to another company. 24 hours and $10-15 later I have something that is typically ready to go.

4. I try to stay away from raster artwork as much as possible. The only time I use it is if I create it myself from a vector. I don't trust the average raster artwork. We've tried just running something off the web or something customer supplied and the end product is typically disappointing.

Ruben Salcedo
03-19-2012, 1:55 PM
I use Topaz DeJPEG 4 plug-in in Photoshop that I believe also works in Photo Pain,
it does a decent job in eliminating the compression specks in jpegs, then I resize it
in Gnuine Fractals now call Perfect Resize 7, there are other plugins or programs for resizing images.


Michael Hunter
03-19-2012, 2:21 PM
I generally find it much quicker to hand draw vectors over the typical poor logos people send.
I say hand draw, because the tracing tools rarely do a good enough job and cleaning these up takes much longer.

For lettering, it is often quicker to use a similar typeface, convert it to curves and tweak the few letters that are really different.
Unless you know the name or strike lucky, searching for typefaces can take hours!

I rarely charge for file prep and setting up, but all my working files are MINE and I make a big charge on the rare occasions that someone wants them.

Dee Gallo
03-19-2012, 2:34 PM
I'm with Michael on this one - you can waste more time and effort trying to fix something than just doing it yourself with the drawing tools.

I recently had a customer who REQUESTED jepgs of some campaign materials for a printing job. I told him it was not a good format, but he INSISTED. Then, when they tried to use the files, they complained about the artifacts (opened in PhotoShop no less). I made PDFs of all the samples and color seps from the CorelDraw files and all was well. Sometimes they just have to see it to believe it..and pay through the nose for it to accept it.

~ dee