Any artist that wants to sell their work in the modern age needs to know how to best to optimize it for computer viewing and print, even if they never touched a computer while they were making the actual art.
First of all the golden rule: NEVER POST HIGH RESOLUTION IMAGES ON SOCIAL MEDIA. It is good for business to show off your work online, but if you share high quality files, why would anyone buy a print from you when they can just print it themselves for a fraction of the cost? Don’t post anything bigger than a cell phone photo (72 resolution and a max un-pixelated size of around half an a4) or you’ll just end up with your art getting stolen.
Now that we’ve established how bad high resolution images are, let me explain how to take the highest possible resolution images of your work. Maximizing the printable size of your art will extend the range of products it can be printed on, raising your chances of selling the work. Just make sure the public doesn’t have access to those files.
If you can scan, PLEASE DO. A scanner analyzes work much more closely then even high end DSLRs can, giving you higher resolutions from scans than photos, and often allowing the work to be printed larger than it’s actual size.
For excessively large work, like this exceptionally verdant 4.5x3ft skull illustration, photo-merge techniques are recommended. This is recommended over a single photo because the actual work exceeds the maximum printable size of a single photo taken with my camera. This way the tiny details in this overall very large work are preserved, and it can potentially be printed at actual size. To get the digitized version of this work, I needed balanced lighting (no one area is more brightly lit than another), a dslr camera, a drawing tablet, and adobe Photoshop.
The technique for this type of photo-merge is quite different than that used in a panorama. While you want to maintain manual zoom and focus in both cases, rather than turning it from a fixed point like a panorama you want to shoot along a plane immediately in front of the lens. Imagine you are holding the camera with the lens right up against a pane of glass that’s between you and the subject. Keep the camera at a tight zoom the whole time and keep the camera steady. About 6-10 shots should do for this work specifically.
To merge the photos, simply select to pictures you want to include in the merge and put them all in the same folder. for the best results you need about 1/4 overlap, but if there are too many photos it can overload the system, so it’s important to be judicious when selecting photos. Once you know which pictures you’re using, go to Photoshop and select file->automate->photomerge. Press browse in the menu that pops up to select all the photos in your folder. Leave the settings at default the first time you try.
While it’s not usually necessary, for this piece I’m going the extra mile and isolating the skull from it’s background so it could float an any color t-shirt or mug. I am using an intuos 4 wacom tablet with PhotoshopCS6. I have my newly merged (and heavily backed up) photo up, and the first thing I’m going to do is unlock the layer and grab the eraser tool. Rather than using the selection tool to get rid of an unwanted background, going along the edges up close and erasing the background by hand eliminates the risk of ragged edges and is much more precise than the photoshop selection tool will be any time soon.
After that, different types of printing will need different steps, but this guide should at least help you make a nice file to start with.