Printing BIG

The 'Bubbling Cauldron is going to the Earsham Street Gallery in Bungay next month and its going to be presented as a 1 metre wide print on C-type Matt paper, framless mounted on MDF. Taking the step to print your images larger, using an outsourced company, requires a good deal of thought and consideration. Don't just send off the original processed file and hope for the best.

Here is my workflow and hopefully it will be of use to anyone thinking of making larger prints that require a commercial printing company.

Stage 1: Process the image at maximum resolution from the original raw file. I'm not going into detail about my processing as I am focusing on the workflow for print production. Once I am happy with a small print, I print the image as large as I can on my home printer. My Epson 3880 gives me beautiful prints up to A2 size and it really gives me a feel for how a larger print is going to look (see first image). You should view it in a similar light to where the print is going to be viewed, this helps to assess whether you have the colour and brightness of the print about right. In the case of the Earsham gallery, that means, bright white light against a white background (not yellow tungsten light in my office for instance!). At A2 size I can easily see if I missed any sensor spots or have any processing problems, you don't want to go to the expense of producing a £200 print and THEN notice some obvious flaw in the image.

Stage 2: Up sizing the image for printing. I prefer Qimage to interpolate the image (where an algorithm is applied to increase the number of pixels and hence image size). There are limits to the amount that you can increase the number of pixels before the image looks degraded to the naked eye.  In this example I increased the original size of the image from about 5000px wide to about 12000 pixels which provides a file printed at at 300 pixels an inch to make a 1 metre wide print  (sorry about the unit swapping there).

How do I assess whether my image quality is okay for the image size I have created?   I print out smaller crops of the full size image to see if the print looks pixelated or out of focus (see second image as an example of what I printed). Print the crops at full size otherwise it is a pointless exercise, I like to make a crop that fits onto a A4 sheet. You should also consider viewing distance in your assessment, as this has a big influence on the apparent quality of the image. The larger you print, an apparently sharp region of the print may start to appear unacceptably out of focus (its all about circles of confusion but lets not go there today).  If the image is unacceptably pixelated or out of focus you are going to have to print at a reduced size, sorry about that but you could always view it from a long long way away .. smiley face.

Stage 3: Print sharpening.
All images need print sharpening to compensate for the fuzziness that occurs when ink is squirted onto paper i.e print bleed (in the case of a Giclee print). While up sizing the image, I add different sharpening values to the image and print them out separately for assessment. Note: print sharpening should be happening with stage 2 and is assessed at the same time as image resolution. The full size crops are checked to see which amount of sharpening is appropriate i.e. no apparent sharpening halos but sufficiently crisp printing. REMEMBER if you have print sharpened your image TURN OFF sharpening on your program that sends the image to print, you don't want to double sharpen!!! Remember this file is being prepared for an outsource printing company that won't be sharpening your images (make sure they don't).  

Note. There is an exception where home printing won't be any help to choose the correct sharpening, a professional C-type print does not use an ink squirting process so ink bleed isn't an issue, the only way to assess how much sharpening is needed for a C-type print is to get test strips done with the printing company.

Stage 4: Prepare test strips for printing. The printspace prints a 1 inch by 30 inch strip on your choice of print production and paper choice for around £3 a strip (see final image below for an example of a test strip). Again, you must print full size, so you can assess correctly the upsized and sharpened file. I crop a full size 1 inch by 30 inch slice out of my image, in a region that will provide a test print with a good range of tones and textures. Upload the test strip file to Printspace and it automatically recognises the format and charges you accordingly. Warning, you get the size wrong even by a tiny bit and you won't get the test strip pricing. I usually try a couple of different papers or production methods for test prints. Once the test prints are returned you can compare these strips with your home made strips (my home made test strips aren't 30 inches long but a slightly smaller crop for my A2 paper).

Following assessment of your test strips you can choose the full size image that corresponds to the best strip (name the files sensibly for later reference) or re-adjust your image and send off another test strip for another assessment. Remember, when you outsource your image for printing, your image is printed using a different printer profile to your one at home, you might see differences EVEN if you soft proof at home with a printer profile that the company gave you. So don't skimp, get some test strips done if you are producing an expensive print. So far, my images at home look remarkably similar to the prints produced by the Printspace (probably helped by having a calibrated monitor) so repeat adjustments are relatively rare. Its worth doing a range of strips as you only have one P&P cost to bear. which is around £5.00

Printspace offer C-type and Giclee (ink jet) prints, they are different production methods but the main consideration is that C-type does not print with black inks (it involves the use of light sensitive paper with three main dye layers—cyan, magenta, and yellow—that together form a full color image) and I see a very slight colour cast using this method on my black and white prints (My test prints picked this up). My test prints have shown that C-type prints look fabulous for colour images so 'Bubbling cauldron' was printed up using this process. One consideration is paper texture, if you are going to use an acrylic seal on your print (Bubbling cauldron will have a matt acrylic seal as it won't be protected under glass) the paper must be smooth (C-type is a smooth finish paper). If you are framing in a classical fashion with glass, then any paper choice is possible and this might be your framing choice if you want those lovely arty papers. The same workflow is used for canvas prints but I use 'Digital labs' for this output. Protective surfaces can also be applied to your canvas prints so ask your production company about surface treatments.

Always speak to the print production company for advice before production, ask them about the colour space and file type they require, always check whether they are print sharpening or image adjusting as a default, you don't want your images double sharpened for instance. Both 'Printspace' (http://www.theprintspace.co.uk) and 'Digital labs' (http://www.digitalab.co.uk) can handle images using ADOBE RGB and sRGB colour spaces. The files have now gone for full size printing. I am waiting to see how they look in the Earsham gallery, wish me luck!




Comments

  1. Good luck -- not that you need it. Thanks for the detailed info on your approach to up-sizing and printing to large scale.

    (This is a more-or-less duplicate of a comment attempted in Google+ using an iPod late at night. Still fumbling with both. Please pardon any repetition.)

    Michael

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  2. Thanks for the post Michael..I wait with baited breath :)

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