RE: solarplate images up on my website
Hi Jon, thanks for the information... I feel it's worth to try. BTW, another option *which will only work for persons who use digital workflow, who can find a printshop that has imagesetter and doesn't charge too much for negative printing*, can be: Making negatives with the aquatint screen incorporated into them - so they can be printed in just one exposure!? I tried to make one by by resizing an image to desired output size (7x10") @ 225dpi (1). (Let me describe why I use 225dpi: Since the final negative will be 1800dpi, I need to use a screen resolution of 1800 / 16 = 112.5dpi in order to get all the 256 possible tones + I need to multiply this intermediate figure with 2 in order to minimise sampling artifacts. Therefore my source image's resolution should be 1800 / 16 x 2 = 225dpi.) Then I applied the following curve: (input-output pairs) 0% - 0%, 50% - 50%, 100% - 80% (2). (What I do here is compressing the tones so that maximum black becomes 80% in the positive.) And finally I converted the grayscale image to bitmap (Input: 225dpi Output: 1800dpi Method:Diffusion Dither). See the result below: http://www.loris.medici.name/single_exposure_1800dpi.jpg The left side is the bitmapped file sized to "Print Size", the right side is the same file at 100% magnification. If the blacks are OK (= no open bite) with this type of negative, the next step would be printing a digital step tablet (exactly using the same settings / making the same modifications) and designing a process adjustment curve for your specific materials and working conditions... Here in Istanbul imagesetter printing prices are quite low (less than $1 per 9x12" negative @ 3600dpi output resolution - using a 225lpi screen), so I would be happy to print some small negatives with different settings and send to few of you to let you try... But this will only work for you *if you have access to an imagesetter for relatively cheap fees*. Regards, Loris. -----Original Message----- From: Jon Lybrook [mailto:jon@terabear.com] Sent: Thursday, February 22, 2007 7:31 PM To: alt-photo-process-l@usask.ca Subject: Re: solarplate images up on my website Thanks Loris, Sounds like this should work, but I don't know the details involved with how an imagesetter works. Maybe someone else could comment. I know they DO have expensive software to precisely generate screens...so there must be a reason. One time I tried printing out screens myself on Pictorico. Comparing them to imagesetter output showed they are worlds apart. Under a lupe, the inkjet output dots were much bleedier, fuzzy and imprecise. Imagesetter output was crystalline. Maybe inkjet technology will improve to this level someday, but it ain't there yet. We still need some way to get good film output once all the imagesetters die off. Keep in mind when talking with Copygraphics, there were two different methods Peter Ellzy used to create my 1800 dpi screens two years ago. One used a software called "Ice Fields" - some proprietary software that created a stochastic image from a normal one. I didn't like the results using that one as much as the one using the 'normal' approach -- whatever that may have been -- maybe Photoshop, but I don't believe it was. I spoke with Duane, the owner of Copygraphics yesterday and made him aware people are interested in the 1800 dpi screen I use and that, among the files in my folder on their computers from several years ago, the one NOT made using Ice Fields was the one I personally preferred and was recommending to people. He seemed to understand my concerns and said he'd dig more into my old data and verify what was going on. I'm hoping they find my old files and that they are able to output them without the striation problems reported earlier. Keep in mind, some people have reported that 1200 dpi stochastic works fine for them and I guess that level of output is problem-free at Copygraphics... Jon Loris Medici wrote: Dear Susan and Christina (and all), Why can't you make your own 1800 dpi 80% stochastic screen file yourself in Photoshop (*1), save it in .eps format and give it to a printshop running an imagesetter (whether they have the special software or not) to print it directly (without applying rasterization in their RIP)? Steps for (*1): 1. Create an empty image (Mode: grayscale, resolution = 225 dpi, size = according to your need) 2. Fill it with the appropiate gray tone (20% Luminosity) 3. Change the mode to bitmap (Output: 1800dpi, Method: Diffusion Dither) 4. Save it to an .eps file (they should open it at 1800dpi, size exactly the same is in step 1) See: http://www.loris.medici.name/susanv_1800dpi_screen.jpg Don't you think that the generated pattern looks like original aquatint pattern? This is a 8x10" file that I processed as listed above (original pixel dimensions: 1800x2250, bitmap pixel dimensions: 14400x18000). Left side the original tone, right side the stochastic pattern at 100% magnification. When you scale the file on the right to "print size", the tone is identical to the left side... If that works somehow, you won't have to be extra careful - to not damage the screen - when printing; you're going to have your file printed again if your aquating screen gets damaged (somehow). What do you think? Am I talking nonsense - or do you think this is worth to try? (I can send you a sample negative if you like - here in Istanbul, imagesetter printing fees are very very low...) Regards, Loris. -----Original Message----- From: Christina Z. Anderson [mailto:zphoto@montana.net] Sent: Thursday, February 22, 2007 4:03 PM To: alt-photo-process-l@usask.ca Subject: Re: solarplate images up on my website I second this, Susan, Yesterday I called all around. No one has imagesetters anymore. One place has one up in northern Montana, but the other problem is the software capable of doing stochastic is $50,000. He can do a stochastic right to PLATE but not to film. But what do we do when the last imagesetter goes out of biz? I mean, would it be the same if we did a digital one and projected/enlarged it onto film ourselves, I wonder... Also, the notes I have on screens so far: 1800 dpi, 80% density; from Ross 20 or 40 microns and that stochastic is 2 different diameter dot sizes of diamond shape. I don't even know what all this means, what a micron is--I assume the 20 micron is a finer dot... I printed out Jon's entire website and keep referring to it. Especially the little jpg of the different exposures and dots--very helpful, Jon. Chris ----- Original Message ----- From: "SusanV" <susanvoss3@gmail.com> To: <alt-photo-process-l@usask.ca> Sent: Thursday, February 22, 2007 6:45 AM Subject: Re: solarplate images up on my website Dear gravure folks... I got an email last night from Copygraphics, and they believe they have the problem with the stochastic screens sorted out. Yay! I have tried to find someone around here to make me one (a stochastic screen), and came up empty. it seems that even long established printing shops have gone digital. One place told me he gave his imagesetter away a few months ago! (and those things are lot of $$$$$ ) Another problem is that they aren't used to making stochastic screens... that's a random dot pattern rendered by special software that not all places even have available. so... I highly advise getting a screen now from copygraphics and taking good care of it. susan gravure blog http://susanvossgravures.blogspot.com www.dalyvoss.com
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