Simon Buckley wrote: (clip) Any other pitfalls(apart from profiles)?
Oh what a tangled web:
ppi=pixals per inch (pixal resolution) dpi=dots per inch (printer resolution) lpi=lines per inch (screen resolution) p=pixals What dick says below:
dick.roadnight (clip) You need to find out the preferred PPI options of the printer to be used - - they will tell you they can zoom it to any size, but they would loose a great deal of detail by doing so.
is good advice
But Photoshop currently has a maximum 2gig filesize limit,thus a 60"x60" can only reach 446ppi. The printer would have to resample.I would try interpolating up the file to 1,8000 pixels square for printing at 300 ppi, but if the output will be to an Epson (e.g. the 44 inch 9600, which that nice man at Newbury has) they would get a better result printing at 720 ppi.
Errata:
Most (if not all) piezo inkjet RIPS and/or screening algorithms are based on 720x720 dpi, meaning any data exceeding 720ppi (at 1:1) will be interpolated down anyway to accommodate dot firing patterns (applicable to Epson X3 head technology and the like). Higher resolutions such as 'True'(sic) 1440x1440 dpi are achieved through variable-dot interpolation. Because variable dot algorithms are used to smooth blending to achieve perceptual continuous tone, 1:1 dot transmission is effectively achieved at 360ppi 1:1 as the 'middle pixal' is interpolated for blending anyway. In the vari-dot world the difference between 300ppi and 360ppi is visually redundant at 1.5 meters when printing to anything but high gloss film (except to the most discerning eye). Media blending from ink bleed buys you even more resolution forgiveness. The difference from 240ppi to 300ppi is another logical interpolative step. Quality also depends on the screening used: error diffusion leads the pack yet is avoided by many large format printers because of the extended RIP-time and expanded RIP-file sizes.
If you want to go big, big at extreme resolutions (which several of my clients do, even though the results are demonstrated negligible) and you want to pack one file on one CD, work on it in 16bitTiff as far as you can go, convert to 8bitTiff, then save as PhotoshopPDF (Image interpolation on) or JPEG (max quality both). Most image output services can handle these file types. If they can't, ask them why not. Places have been known to dump tiffs and other file types into page layout applications to keep their file handling times to a minimum. Most (if not all) Level 3 RIPs can handle (flattened) Tiff, PhotoShopPDF and/or JPEG as drag n drop items (if that is how the printer prefers to work). Most others have or should have PhotoShop to handle such files. (Of note: if they choose to manipulate or further interpolate your file, 8bitTiff will outperform PDF, PDF will outperform JPEG, in that order.)
Keep in mind many printer's RIPS begin to bog down at 840MB or max out at 2gig (RIP file sizes, not your image size).
Quality also depends on the screening used: error diffusion leads the pack yet is avoided by many large format printers because of the extended RIP-time and expanded RIP-file sizes. Many medium quality RIPs cannot handle file sizes larger than 540MB.
If going over to other than inkjet (like say a Chromira) most optical and/or LED-based devices interpolate 300ppi to a perceptual 425ppi output or better. A 250ppi image interpolates up to 340ppi perceptual output.
My recommendation:
5'x5' 240ppi image comes in at one 643MB 8bitTiff file. One CD. That beats the hell out of many of the files 'pros' provide us large format folk on a regular basis.
...just a few notes from who knows where.
--
joel johnstone
Color Canuck
(two cents from my nickel's worth)
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