Photographing a large art work

February 20, 2019  •  Leave a Comment

An artist friend, India de La Rosée, asked me to create a reproduction of her work Longs Baisers, a canvas sized 200 x 20 cm.  The quality had to be good enough to allow full-size copies to be printed on canvas, equivalent to the original in detail.  This was quite a challenge.  The work is a multitude of lipstick kisses of many different shades on a white canvas, and tells a story of lonely souls waiting for love (see the artist's web site for more about the work).  It is particularly striking because of its size.

First, to photograph the work at sufficient resolution I took three shots of one-third sections of the canvas.  I lit the subject with two studio flash units with softboxes, set either side at 45°, which provided the all-important even illumination.  I used the High Resolution shot mode in my Olympus OM-D E-M1 Mk.II camera, with the 12-40 mm f/2.8 pro lens set at its longest length (80 mm full-frame equivalent) to minimise perspective distortion, and at f/8.  I also tried a longer lens, the 40-150 mm f/2.8, but preferred the result with the 12-40. 

In the High Res mode of the E-M1 Mk.II, although the imager is 20 Mpixels, the camera takes eight sequential shots, moving the imager a tiny bit between each shot, and composites a single high-res image of 80 Mpixel, presented as a raw file (it also produces a 50 Mpixel jpeg, which I did not use).  With the camera mounted on a sturdy tripod, this works really well.  When using strobe lights, as I did, the camera can be programmed to wait, for 2 seconds in my case, between each of the eight shots to allow the flashes time to recharge.  I also set a 4 second delay before the first shot to allow decay of any vibrations caused by me pressing the shutter release.

The three images looked good in Lightroom and clearly had high enough resolution and contained all the needed detail.  I loaded them into Photoshop and combined them into a single image, with each shot a separate layer, allowing me to make small adjustments to ensure uniformity of luminance, and pay attention to the "joins" between the sections, which became invisible.  I also tidied up the edges of the image where the canvas edge was visible.  After cropping for the long thin shape of the work, the .psd file was a massive 630 Mb.  I was pleased to have a powerful enough computer (see earlier blog) that could cope easily with working on such a large image file.  At one point during processing when I had many layers and tried to save, Photoshop informed me that I had exceeded the maximum 2 Gb file size!  Merging some layers avoided this problem.

Faithful colour reproduction was absolutely essential in this project, with subtle variations of pinks and reds in the kisses.  Having calibrated my Eizo CS2420 display with my Spyder 5, I used various adjustment layers and masks in Photoshop to make fine adjustments, comparing always with the original viewed in daylight.  A painstaking process but ultimately fully successful.

Although the intention was ultimately to send the image to a print service for printing on canvas, I wanted to first produce myself a print for the artist to review and check for its detail and colour correctness.  I used my Canon PRO-100S printer for this, printing on Canson PhotoArt HD Canvas, of which I bought a 12 m roll, 43 cm wide.  The longest length that I can print is 67.6 cm.  This seems to be a limit imposed in the printer driver, there's no real physical limit, provided the canvas can be fed into the manual feed tray.  But I could find no way of avoiding the 67.6 cm limit, so I printed the image in three sections, with a small overlap, and glued them together with Copydex.  This was good enough to allow India to review the printed work.  She spotted a few further adjustments to be made, which I did and produced a further trial print that both she and I were happy with.  This I exported from Photoshop as a PDF, sized 35 Mb, to be sent to the print service.  The final image is 23622 x 2362 pixels, which is exactly 200 x 20 cm at 300 dpi.

After consulting other photographers for recommendations of canvas print services I contacted several.  Most were not able to print a 2 m long canvas.  Finally I found one who could and sent them a small 20 x 20 cm section as a sample so that we could check the colour reproduction.  The final full print was of very high quality.  Actually we had two prints produced, because the printer's canvas is 60 cm wide, so we could print a second alongside on canvas that would otherwise be wasted.  The first print has been stretched onto a custom-made frame at a local art store and framer.

The final print is an excellent reproduction of the original, in detail and in colours.  This is very pleasing.

See more about the work on the artist's website:  https://indiadelarosee.com


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