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Discussion Starter · #1 ·
i've been searching for a good explanation for the purpose of RIP software for the last two days and i haven't found much.

during my search i've been able to do everything a RIP is suppose to do in photoshop, except for control the thickness of ink the printer puts out.

i can change the contrast and saturation on my printer (epson rx595) though through the windows control panel which does seem to make my prints on normal paper blacker, but it also seems to make the ink bleed slightly more (i don't have any transparencies so i'm just doing tests on normal paper).

but lets say i had an epson 1400 (which i could get for $200 form the epson store). supposedly it has the ability to vary the thickness of the ink, but for some reason you need to spend $500 (eg AccuRIP) on some software to make it do so? how can the software cost 250% what the hardware does? that doesn't make sense to me at all. it seems like the drivers to allow you to control that stuff would come with the hardware if it's capable of doing such things.

i know RIP can do halftones , alignment marks, and all that jazz, but so can photoshop.

i knew nothing about photoshop a few days ago, and now i can seperate a full color photo into 4 layers (CMYK) and do halftones on each at different angles in under 5 minutes. and the process doesn't use the crappy halftone filter either :D

since i wasn't able to find a good explation of this total process during my searches, i'll gladly make another thread with step by step details if anyone wants me to.

all i want to know is if RIP's have any value other than controlling the thickness of ink and what spray heads get used.

to me it seems like i would be fine just getting some specialized ink (like that BLACKMAX stuff from fastink) that is supposedly more opaque that you standard stuff. even though it is $150 for six cartridges which seems a little steep to me.

i've never screen printed before though so maybe there's something really important i'm missing.

could someone please fill me in on what makes RIP's worth the money if you already have programs like photoshop and illustrator?

thanks :)
 

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Printing TRUE halftones is going to be an issue without a rip. As far as the ink layer, I have had good results with just using the highest quality settings in the printer driver settings and set to print on glossy media.
I would be interested to see what method you used to output halftone transparencies from within photoshop. Plus you said you didn't use the halftone filter, and I'm assuming you're not talking about the bitmap halftone conversion function either.
On the other hand ghost script is free, and it works.
 

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Discussion Starter · #3 ·
actually i am using the bitmap halftone conversion.

first i make 4 duplicate layers and swithc them to CMYK mode

then i adjust the levels by subtracting out everything but the desired color (eg. subtracting M Y and K for the C layer)

once that's done i desaturate and switch the grayscale mode

then i switch to bitmap mode and convert to halftone

i then copy the whole image and back up a couple steps (when you do the bitmap halftone thing it merges all the layers down)

repeat 3 more time for the other layers (and make sure to switch the angle by about 15 degrees everytime) and you got your CMYK halftones.

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now, what do you mean by printing TRUE halftones. and how is a RIP gonna help a printer achieve TRUE halftones?

i'm assuming the image i'm creating in photoshop are TRUE half tones because the only color used is 100% black.

thanks for the heads up about ghost script.. i'll check it out.
 

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Well, I did a little comparison of the two methods and I really don't see a big difference in the shape or quality of the dots- zoomed way in. In fact they're almost identical, the only difference being the Ripped file is at 960dpi, and the photoshop file is at 300dpi. I'm going to print both out on pain paper and see if there is a noticeable difference. Have you done any 4 color process shirts with your method?
 

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Discussion Starter · #6 ·
i haven't done any screen printing period :)

i'm in the process of learning all i can before i purchase my first setup. i've noticed alot of the equitment seems to be way overpriced and i plan to build as much of it myself as i can (eg. i can easily put together one of the $3000 MH exposure units for less than $300). hence the reason i'm question the $500 RIP software. i definately don't know anything about programming :)

i did however do an experiment with my printer.

i replaced the black in those 4 halftone layers i made with the actual color they would be on a screen press then printed each one seperatly on the same page.

i was very pleased with the result at 230dpi (i figure since this is the mesh size i will likely use there's no point in higher resolution images)

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about the RIP software.... does it make printers actually print more accurately or give them the ability to print higher dpi's?
 

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Discussion Starter · #7 ·
Okay here's the output from both- remarkable resemblance...
The 960dpi file is through ghostscript..
The 300dpi file is through photoshop's bitmap conversion filter.
what kinda printer did you print those on? that is a scan right?
 

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No, it's the actual bitmap file as seen in ps. I did print on paper- I can't see a difference. Since the files are just bitmaps, they'll print to any printer- I printed these off a laser printer-I'll scan and post later.
BTW, I built a metal-halide exposure system with a blanket and vacuum that I'm very proud of- Burns photoplymer in 15sec and dual cure in 45sec- with perfect detail. Cost less than 350.00.
 

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You should try GS and GV as they are free. In Corel the halftone dots were there but not as dense as with GS. The dots were made up of smaller dots and the edges had imperfections. Go grab a magnifying glass and take a good look at your outputs. The better defined and solid the dot the better screen you are going to get in my estimation. I have Flexi pro and it has a rip but havent tested it yet. I dont use Photoshop much so havent played with halftones in that program. Same goes for AI., I have it but havent tested its halftone production.
 

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Discussion Starter · #10 ·
so you added the vaccum to your exposure unit eh?

i was thinkin about doing that, but i don't know where to get that stretchy black rubber stuff or that type of vacuum pump.

please do tell :)

also what wattage bulb do you use and is it a specialty bulb or just your run of the mill MH?
 

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The bulb is a 400 watt metal-halide with ballast. I got it from a local electrical supply house. I use a small shop vac for the vacuum. I'm telling you the thing ROCKS!! I built one 5 years ago and sold it. The one I'm using now is second generation.
 

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Discussion Starter · #13 ·
wow only 400watts and it exposes screens 15-45 seconds?

that goes way against all the stuff i been reading.

they're talkin minimum of 1000w MH which exposes screens in like 10-20 minutes.

lol i dunno :)
 

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I just did a 600dpi scan of some film I outputted from Flexi-RIP, and guess what??
The dot shape and clarity and size is identical in all three instances. I never knew the dots from my Flexi rip were that jagged through a magnifying glass, That's why I didn't think the halftone conversion in PS would work. The dots using that method are really jagged. But I guess all dots done for lower reolutions will look the same. I wonder how 1200 or 2400dpi would look close up?
 

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Yeah...a magnifying glass will show things you never see when looking at two different output sources. On printed paper I think you get more uneven results as the ink tends to spiderweb into the paper fibers.
 
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