Large image processing

[Jonathan Cross]

I have been asked to take a photograph of a painting by our local museum.  It is roughly 6ft x 4ft in portrait orientation.  A life-size print at 250ppi would require an image of over 200MP.  I have 2 alternatives in mind. First rent a Sony A7r4 and use pixel shift to get a 240MB image.  Second, use my Fuji X-T4 to take overlapping images and combine as a panorama.  The panorama could be done 2 ways.  Either take a few from one position and use PTGUI, then Gigapixel to upscale, or take more, probably as two or three overlapping sets essentially as vertical linear panoramas and combine them. The only problem with the linear approach is what software to use to combine the images. 

Any advice would be welcomed, including how Lightroom Classic handles a 240MP image, either as a RAW or as a JPEG.  I can get a life-size print made by a UK agency.

Thanks,

Jonathan

[Peano]

You don't need 250 ppi for a photo that large. It depends on the viewing distance. Talk with the print lab; tell them where it will be displayed and how far viewers are likely to stand from it. I suspect your photo will call for far less than 250 ppi. (Note, print labs often use "dpi" when they mean "ppi." The "dpi" in this chart means "ppi.")

[Garnick]

Hi Johnathan,

Other than the issue of resolution, I think your next possible problem might be the look of the print.  In other words, unless you send the original Art Piece along with the image file to the lab there is zero guarantee that the final print will match the original in various ways.  Perhaps you should have an in-depth conversation with the curator of the museum about this issue before you spend a lot of time with the job.  Just my opinion of course, but an informed opinion based on many years of reproducing art on various substrates.  It's often a PITA, but the final outcome is what the customer needs to see of course.

Just my thoughts   

[langier]

First, figure out your end goal, is this for the web, for 100% reproduction, etc., etc. That should give you guidance on where to start. If the original painting is on canvas, then resolution may not be as critical since canvas has a nice way of fixing things ;-)

For a couple of my clients, I need to get large files for print of the original artwork, much of it larger than my camera can properly record for full-size prints on paper and other material. My solution is to use what I have, a D800 and then using one of my sharper lenses, shoot it in sections moving the original past the camera and the lights for consistency and ease in lighting. Some work takes 2-3 shots, other take more. It's pretty easy to assemble directly in ACR after importing the files, plus if there's any issue with geometry in the automatic assembly, it's easy to fix there along with correcting the lens short-falls.

For color matching, there's a lot of info on the web to help you but having the original available with controlled and consistent lighting when you test print is key to the most accurate color. Unless your client has deep pockets, this will even be more critical. My goal is not to make things 100% since that's almost impossible but to get it close and what's called "pleasing." What that means is that it's about 95% or better accuracy and for most people, that works well.

In all reality, few, if any, will ever have the reproduction next to the original, let alone having them both under controlled lighting. Years ago in the early 1980s, my friend and colleague was deep into making things match. He had a fine-art reproduction done of three of this watercolor paintings produced to sell as a limited edition. It looks weeks to prepare and the printer was crying along with him at how beautifully the repros matched the originals. It was expensive, 6-7 colors on the press using spot color and touch-plates, totally over the top. Yet so was the bill and in the end my friend, now in his late 80s still has a bunch of the edition in his studio...

I've worked with him for years and we sit together at the screen and print as we go. If it's close and pleasing today, he's totally happy since he's finally figured out that 99.9% will never buy his original and a bunch of reproductions and then hang them side by side...

He's happier, I'm happier and the clients are very happy! Best of all, we work quickly and more efficiently and still produce a superior print that we all are proud of, realizing that 30-40 years ago, this was our dream to produce and the quality is even better than we could have ever hoped for.

[Jonathan Cross]

Thanks for the comments so far.  The painting is oil on wood, done between 1926 and 1928.  It is a map of the local area with lots of buildings and landmarks and people on it, and was painted for a Lady-in-Waiting to the Queen; the recipient lived locally, according to a biography of the artist.   

I doubt if an image will be viewed alongside the original, but has been requested in case an accident happens to it as it is somewhat fragile.  The ability to print lifesize would be appreciated, but very accurate colour matching is not a prime requirement.  It may well not be as vivid as it was.  The museum inherited it when it was found in a damp local Government cellar!

Jonathan

[krseals]

Jonathan,

Do you think the new Super Resolution in ACR would help you get the size you might need?

Ken Seals

[JRSmit]

I have been asked to take a photograph of a painting by our local museum.  It is roughly 6ft x 4ft in portrait orientation.  A life-size print at 250ppi would require an image of over 200MP.  I have 2 alternatives in mind. First rent a Sony A7r4 and use pixel shift to get a 240MB image.  Second, use my Fuji X-T4 to take overlapping images and combine as a panorama.  The panorama could be done 2 ways.  Either take a few from one position and use PTGUI, then Gigapixel to upscale, or take more, probably as two or three overlapping sets essentially as vertical linear panoramas and combine them. The only problem with the linear approach is what software to use to combine the images. 

Any advice would be welcomed, including how Lightroom Classic handles a 240MP image, either as a RAW or as a JPEG.  I can get a life-size print made by a UK agency.

Thanks,

Jonathan

Why 250PPI?
Anyhow i believe the megapixel limit of current version of lightroom is 512mp

[Jim Metzger]

As an aside, have you figured out your lighting for an image that big? Oil on wood will have lots of specular highlights and you will need to be careful with polarizing to keep the image brushstrokes "3D" while minimizing the highlights. It will also be difficult to evenly light an image that size.

I do a little artwork reproduction for local artists, it is difficult and I wish you good luck.

[Jonathan Cross]

Yes, I am aware of the lighting issue. I am hoping that it can be taken outside on an overcast day. Thanks for the comment about a polariser. The painting is 93 years old so I do not know yet what the highlight situation actually is. I will give it a try though, ‘Nothing venture, nothing gain.’ !

Jonathan

[Chris Kern]

I have been asked to take a photograph of a painting by our local museum.  It is roughly 6ft x 4ft in portrait orientation.  A life-size print at 250ppi would require an image of over 200MP.  I have 2 alternatives in mind. First rent a Sony A7r4 and use pixel shift to get a 240MB image.  Second, use my Fuji X-T4 to take overlapping images and combine as a panorama.

I have limited experience photographing two-dimensional art, but my experience shooting three-dimensional art (my wife's sculptures) leads me to suggest that you opt for the Sony.  Anything you can do to simplify the capture will make it easier to achieve the desired result.

The single A7r4 file will result in a simpler workflow than stitching the X-T4 files because it will eliminate any threshold issue of alignment (parallax) errors.  You may need to go through multiple iterations to get the camera alignment and lighting the way you want it, so any complexity you can avoid will pay a dividend in reduced frustration over the course of the shoot.

Also, if the museum ever needs to display the life-size print of the 6x4-foot painting, the slightest misalignment will be visible to visitors.  And even if the image winds up only being used for archival purposes—e.g., scholarship—no doubt it would be important to avoid any artifacts that might be visible on close inspection.

One other suggestion based on high-resolution photographs of some 17th Century maps I made a while back: in addition to getting the lighting right to avoid hot spots and specular highlights, I would recommend using a narrow focus stack to ensure that you completely record the texture of the pigment.  This turned out to be useful even on the maps, which were printed on parchment and hand-colored with a relatively thin water-based paint, so I'm fairly certain it would be worth doing for oil paint on wood.  The X-T4 firmware has an excellent focus-stacking capability; I don't know whether something similar is available on the A7r4 or if you would need to use some third-party hardware and/or software.

Finally, my inclination would be to steer clear of AI enlargement tools.  I suspect they present a substantial risk of amplifying any visual elements in the capture that the neural network would interpret as meaningful detail, and subsequently render as objectionable artifacts.  Enlargement tools like Adobe Super Resolution and Topaz Gigapixel recreate a destination image based on the visual elements they identify in the source rather than simply interpolating more pixels.  Museum curators and art scholars are probably even worse pixel-peepers than photographers.