help remove dots from printed image

No matter what mode I use, I get small dots throughout my image.  Using a PM 7600 and an Epson 800 color inkjet.  This particular image is black and white, looks fine on the screen but the darn dots won't go away!

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deserttoadAsked:
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weedCommented:
You need to use a higher resolution for 1) your source image and 2) your print method. Youre probably printing from a 72dpi image and no matter how high you bump the dpi on the printer you will only get a 72dpi image out. In photoshop or whatever youre using set it to a higher DPI in the Image Size dialog.
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deserttoadAuthor Commented:
I scanned the photo (black and white) at 300 dpi, have the image size set to 300 dpi, and print at 360 dpi.

I'm not printing to a postscript printer and I have the mode set to grayscale.
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weedCommented:
Well then maybe youre just too picky. Youre never going to get rid of ALL the dots on an inkjet printed page. Thats just the nature of the beast. An inkjet printer prints in dots. If you dont want dots you have to either buy or take the print to a Dye-Sublimation printer which prints in continuous tone.
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weedCommented:
BTW 300dpi on an epson inkjet is relatively low considering it will go up to 1440dpi
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ArtGCommented:
You are absolutely correct Weed. Most Epson printer use "variable dot technology". Lower resolutions make larger dots, higher resolution makes tinier dots. The Epson 900 has a 3 picoliter dot and the 1160 large format has a 4 picoliter dot. You can't see them because they are too small.
Art
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deserttoadAuthor Commented:
Hi again,

      I'd had forgotten all about this posting.  Got a new G4 and was playing around.  So yes, it is a matter of printing resolution.  Just hard to understand why.  Why would it print dots when there were no dots to be printed?  So is it a relationship between the resolution an image was scanned at, and the resolution it will be printed at?  And if so, is there a preferred setting for each?

deserttoad
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weedCommented:
Dots are just how most printers print. They cant splotch down a solid mass of color in the right shape due to the way ink spreads out and soaks through paper. Even the image on your screen is made up of dots. Yes theyre square dots and theyre directly adjacent to eachother but still dots of a sort. Hence DPI or DOTS PER INCH. Youll notice that if you make an image on screen at 20 dpi it looks really ugly. If you make an image at 2000 dpi it looks much better. The more dots per inch the more detail can be obtained. As far as scanning then printing: I scan slightly above what im going to print at. If im going to print at 1440 dpi i will scan at 1600 or so then scale it down in photoshop. As always its generally best to print at the highest possible rez. There are of course exceptions to this rule. Wide format printers and many dye-sub printers only need 72dpi because of the way they handle the dots. Wide format prints arent meant to be looked at up close anyway so you dont see the weird dot arrangement. Dye-sub printers dont use dots at all. They spred down a solid coat of plastic like stuff which results in beautiful prints but at an outrageous cost. I pay $75 for 18x22inch dye-sub prints and thats with half price discounts.
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deserttoadAuthor Commented:
Well most of it all makes sense now.  Except when printing at a lower rez, the image looks fine and the dots are in the white area around the image.

btw, I can give you points here somehow for helping, how do I go about that?
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weedCommented:
Since the question was left to idle for so long the question was autograded with a grade of C.
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ArtGCommented:
deserttoad,
The reason you see dots in the white area is because it is not "pure" white. It is probably gray or slightly off-white. This is the printer's attempt to represent that pale shade with a few large dots due to the low resolution setting. The best way to get rid of this is to make the white area pure white or remove the background entirely. There is a way to save a tiff file from photoshop with a transparent background. This would eliminate the dots entirely. Or you could replace the background with something different that wasn't so pale.
I have printed a lot of posters at 360 dpi with Epson printers. I sure hope this helps.
Art
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