# Halftone question / regular inkjet printer question



## Ken Styles (Mar 16, 2006)

Hey guys, 
For some reason this halftone thing is driving me crazy. I'm not sure exactly how to use ghostview and ghostscript (even though I downloaded them), I'm not sure how or when they come into play between editing the image/design in Photoshop or illustrator and the final printed negative. Does it just tell the printer to print the halftones automatically somehow on the back-end or is there some kind of special tweaking to the printer settings you have to do or option you must choose right before you print.

Anyway, my real question is:
Say I have a grayscale image and I converted it into a "halftone" image using the options in Photoshop, then why wouldn't my hp inkjet printer not be able to print this image below....and then ultimately burn to a screen and print to a white t-shirt just using black ink? I'm talking just printing the image exatly as you see it below without using any high-tech RIP software or even ghostview and ghostscript..etc.












p.s. don't get me wrong. If I could by a nice new large format epson printer with a RIP software, I would do so in a heartbeat...but at this point i cannot do that.


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## Fluid (Jun 20, 2005)

> Say I have a grayscale image and I converted it into a "halftone" image using the options in Photoshop, then why wouldn't my hp inkjet printer not be able to print this image below....and then ultimately burn to a screen and print to a white t-shirt just using black ink


You can. The issue with the halftone filters is that ultimately the halftones will not be the best they can as a true postscript printer or rip will make. If you make your halftones in PS like you mentioned you should be able to print to a inkjet without the need for a rip. Only issue that may arise is not enough ink on the film (not opaque enough) Most rips will deposit more ink for a darker film positve


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## Ken Styles (Mar 16, 2006)

ooohh, copy that. Thanks again Fluid!


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## tpitman (Jul 30, 2007)

If you're going to use the halftone bitmap feature in Photoshop, it's a good idea to keep your dpi on the high side - 600 to 800 dpi. The file won't be that large since it's bitmap, but the definition of the halftone dots will be about as good as you'll get from this way of doing it. You may want to try that, and compare it to the same halftone file output via a rip or ghostscript if you can find someone to output the file for you. Look at 'em through a loupe and see if there is any appreciable difference, then choose.
There's a post by Richard Greaves somewhere on this forum discussing some of the benefits of using an Epson and a rip, film density and the ability of a rip to lay down more ink, and he's absolutely right. I've gotten denser films from FastRIP than with an HP9800, but the HP films are dense enough that I get full exposure of the emulsion.
Ultimately, you'll have to make a decision as to where the price break is in your positive film device selection where acceptable quality meets affordability. I'm sure screens mounted with capillary film and with shot from positive films from a photographic imagesetter and exposed on commercial single-point exposure units will have better halftone dot definition than those imaged on the inkjet film or laser vellum and homespun exposure units that many of us use. Buy the best you can afford based on the type of work you intend to do with it, and the volume of film you intend to output, but I'm reminded of a comment made in a how to screenprint book I read, and that is: it's T-SHIRTS we're printing, folks. You and your customers will have to decide what's acceptable.


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## MBrhythm (Mar 1, 2007)

I've used the ps halftone. I had NO problem thus far. But i know that using a rip and or postscript will give me a better film. But again... i had no problems with it thus far.


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## tpitman (Jul 30, 2007)

For what it's worth, I just ran a test print of halftone percentages of black out of InDesign through FastRIP on my Epson 2200. I also ran a test print of a photoshop bitmap file of the same percentages through my HP9800. Both on FastPOS film.
I will say that the Epson has been sitting for awhile. I printed halftone seps and solids to check against the HP 9800 output. There appears to be either a slight ghost image to one side of the dots on the Epson, and I'm going to attribute this to the printer being unused for awhile. The HP9800 printing the bitmap file saved at 800dpi, at a line screen of 55 lpi, frankly printed at least as clean a dot as the Epson. Other linescreens were similarly clean. Additionally, looking at the differrent percentages of black printed (20% through 80%), I can't say I notice and discernable differrence between the Epson and the HP. The Epson utilizing FastRIP did print a noticeably denser solid than the HP. Whether or not I can increase the density of the HP's output remains to be seen, but as I mentioned before, I've gotten my exposures dialed in pretty good and I get full exposure of the emulsion with no loss of dots. I pretty much print halftones at 55 lpi. I've also had no registration issues with the HP9800, and I always use 6 registration marks on my stuff (3 across the top, 3 across the bottom. By the same token the Epson always provided good registration from separation to separation.

As I mentioned, the Epson has sat awhile, but I'm not sure that has that much of an effect on the actual dot shape (excepting the slight ghost). Others who have access to both printers might try the same test to see if they get different results. There are certainly others on these forums with more experience than I. I'm just trying to get to a solution for myself that is A: acceptable in quality, B: convenient, and C: affordable. Cheapest is rarely the best, but throwing money at a problem doesn't always solve things either. Just look at the government.


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## Maggie (Jun 15, 2007)

This was very informative thank you. I love this site.


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## Ken Styles (Mar 16, 2006)

tpitman said:


> For what it's worth, I just ran a test print of halftone percentages of black out of InDesign through FastRIP on my Epson 2200. I also ran a test print of a photoshop bitmap file of the same percentages through my HP9800. Both on FastPOS film.
> I will say that the Epson has been sitting for awhile. I printed halftone seps and solids to check against the HP 9800 output. There appears to be either a slight ghost image to one side of the dots on the Epson, and I'm going to attribute this to the printer being unused for awhile. The HP9800 printing the bitmap file saved at 800dpi, at a line screen of 55 lpi, frankly printed at least as clean a dot as the Epson. Other linescreens were similarly clean. Additionally, looking at the differrent percentages of black printed (20% through 80%), I can't say I notice and discernable differrence between the Epson and the HP. The Epson utilizing FastRIP did print a noticeably denser solid than the HP. Whether or not I can increase the density of the HP's output remains to be seen, but as I mentioned before, I've gotten my exposures dialed in pretty good and I get full exposure of the emulsion with no loss of dots. I pretty much print halftones at 55 lpi. I've also had no registration issues with the HP9800, and I always use 6 registration marks on my stuff (3 across the top, 3 across the bottom. By the same token the Epson always provided good registration from separation to separation.
> 
> As I mentioned, the Epson has sat awhile, but I'm not sure that has that much of an effect on the actual dot shape (excepting the slight ghost). Others who have access to both printers might try the same test to see if they get different results. There are certainly others on these forums with more experience than I. I'm just trying to get to a solution for myself that is A: acceptable in quality, B: convenient, and C: affordable. Cheapest is rarely the best, but throwing money at a problem doesn't always solve things either. Just look at the government.


Wow, those of us that do not have the option of printing both ways are grateful that you took the time to print and compare!


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