Making Digital Photographs of Art Work
and editing them using Adobe Photoshop

So you want to make a digital representation of your art work. Ok. I'm going to help, but there are many things to consider, so tackling all the issues at once can be overwhelming. I will try to break it down into bite-sized chunks.

We will discuss:

This tutorial specifically addresses two-dimensional work. Many of these considerations can apply to three-dimensional but typically with 3D art you do not want flat, even light.

White Balance

The many shades of white

Monet haystacks

Light can be many different colors, even light that we see as white. Sunlight at noon is a different color than at dusk. Sunlight on a cloudy day is a different color than on a cloudless day. Indoor lighting is different from sunlight and may be a variety of colors depending on the type of light bulb used. The human visual system is quite sophisticated, and it automatically compensates for these differences. Most of us don't notice changes in the color of "white" light. (You may recall from an art history class that Monet worked on different canvases of the same scene at different times of day specifically in order to capture these different colors of light. Monet trained his eye to overcome our natural adjustment to the color of the light.)

white balance

Digital cameras have a setting called "white balance" which attempts to compensate for the color of the light. Set the white balance setting for the type of light you are shooting in. One of the white balance options is always "auto", which sometimes produces good results and sometimes does not. Usually a specific setting is more reliable. The choices are usually something like daylight, cloudy, shade, tungsten, fluorescent, white fluorescent. Modern compact fluorescent light bulbs may be closer to the camera's "tungsten" than "fluorescent" setting, so sometimes a bit of experimentation is necessary for best results.

gray cards

The camera's white balance setting will get us close to the right colors, but to get even closer we will use a known reference point and adjust to it after the shoot, in Photoshop.

A photographic gray card is a piece of cardboard (or plastic) that is perfectly neutral in tone. It is also a value that is exactly half way between white and black on a photographic scale, but that attribute is not as important to us here as the fact that it is perfectly gray. It has no more red than blue than green, or any other color.

You could mix yourself a swatch of gray paint to serve this purpose, as long as you are confident that the swatch is perfectly neutral.

Include the gray card (or paint swatch) in your photograph of the art work as the known reference point.

Lighting

The concept is simple, but the implementation is not always so. The concept is that you want even light on your piece.

In the example to the left, of a framed photograph with a gray card above it, the light is pretty even, but the light source is causing a reflection on the glass. If your art will not generate any reflections, as might be the case with some types of paper, a camera's built-in flash may work just fine. But anything with dimensionality, like oil paint, anything with glass, or anything with even the slightest reflectivity will bounce direct flash right back at the camera.

And, as in this example, a highly reflective surface like glass will reflect not only the light, but objects. You might see yourself standing there, holding the camera. That wouldn't be so good.

 

In this example I've moved the light source and camera to an angle that would prevent their reflections from showing, and I've made sure there is nothing else that might be reflected in the glass. I've solved the reflection problem but I've introduced two new problems. One is that the light is uneven. The other is that the picture is no longer rectangular in the image.

While it is sometimes possible to even out the lighting in a computer program like Photoshop, unless you're very proficient at such manipulation, it's much easier to make the light even in the first place.

However, it is fairly easy to make the picture rectangular in Photoshop, so we'll accept the angle but correct the light.

How do you do that? Light loses energy with distance, which is why a spotlight is brighter on a nearby object than a distant one. In fact, light loses energy very quickly, so if you're shining one light on your piece from the side, as in this example, the other side will be noticably darker.

 

One solution is to use sunlight, because the difference between the distance from the sun to the left side of your piece and from the sun to the right side of your piece is pretty darned small. With sunlight, be cautious of reflections though.

Overcast light can be ideal. But if the "overcast" is caused by being on a porch or other shaded area, the light may not be even.

Another solution is to use two lights, one from each side. If you have access to a copy stand (see illustration), and if your piece will fit on it, this is a great solution, but it will not solve the reflection problem. If you can remove the glass, a copy stand will provide even light and a correctly rectangular image.

But if you don't have a copy stand, can't remove the glass, or your piece is too big for a copy stand, you'll need another solution.

 

Humans are not particularly adept at seeing small changes in light levels, so making the light even can be tricky. If you have two flood lights, both the same distance away and at the same angle, you'll probably get it pretty close. (This is what a copy stand has.)

I have to ask a question here: How particular are you? If you want the photograph to really accurately represent your piece, you want the light to be really even. If you're using a copy stand or perfect overcast light, you're probably ok, but otherwise you may want to look into a thing called an incident light meter. (Most light meters have a little bubble you can move over the sensor to make it take incident readings.) What this does is allow you to read the amount of light falling on a particular part of your subject. You can move the meter around over the surface (being careful not to change the distance from the surface) and watch the reading. If the light is even, the reading won't change.

This example was made with the camera slightly off to one side to avoid reflection and with two lights, one on either side.

Now that we have our basic digital capture, we need to make some corrections to it. One correction will be the rectangularity, mentioned above, but we'll do that later. The other correction is color. Look at the (supposedly) white mat board in this photo. Notice that it has an orangish cast to it.

Here, again, I have to ask you: how particular are you? Do you care if the colors in your photograph accurately represent your piece? If you don't care, you can skip the whole next section. If you do, read on.

The reason the color is off is because different light sources emit light of different colors. Flourescent is greenish, incandescent is orangish. Sunset is pinkish. Clear sky is bluish. The human eye tends to compensate for the color of the light, so we don't usually notice it, but cameras aren't as good as eyes at this task, so we will correct the color in Photoshop.

Color

Now let's talk about correcting the color.
eyedropper

Open your photograph in Adobe Photoshop.

From the Menu at the top of the application, click "Image" then "Adjustments" then "Levels". On the right side of the Levels dialog you will see three eyedroppers. Click the middle one and then click on your gray card. What that does is balance the colors in the gray card so that it is perfectly neutral in tone. You're done.

If you have something that is (or should be) perfectly, solid black in your image, you can use the left eyedropper on it, but this will turn that spot perfectly black, with not texture. Likewise if you have something that should be perfectly white, with absolutely no texture, you can use the right eyedropper there, but it is rare that you want something perfectly white.

If you use the black and/or white eyedropper and discover that it has gone too far, click "Cancel" and start over again.

Depending upon the strength of the light you shot your photo in, you may need to increase the contrast of the image in order to accurately represent your work. You can use "Image" > "Adjustments" > "Brightness/Contrast" to achive this. Be careful not to give the photograph more contrast than the original.

Squareness

Now you're going to trim off the excess fat and square up the image.

In the Toolbox, select the Crop tool . Click and drag it around your piece. You do not have to be very accurate here. In the Tool Options Bar (under the Menu Bar), click the check box next to "Perspective".

Zoom in on a corner by pressing the space bar and Mac: Command; PC: Ctrl and drag around the area you want to see. Zoom right in there to see the corner.

Click on the little square in the corner of your dotted line, indicating where the image is to be cropped, and reposition it exactly to the corner of your piece.

 

Hold the space bar down and click and drag to reposition your view of your image. Go to another corner and reposition that square. Do the same for all four corners.

Press Mac: Return; PC: Enter to finish the crop.

Proportions

Correcting the length/width ratio

If you were able to photograph your piece exactly head-on, not from an angle, you can skip this step.

If you photographed it from an angle, you have distorted the length-to-width ratio, so now we will correct that distortion. You must know the actual dimensions of your piece to do this step, so grab a tape measure and go measure it. I'll wait.

You're back. Good. Now, in the Photoshop menu bar click Image and Image Size. On the bottom of the window is a check box labeled Resample Image. Uncheck that. Then, in the Document Size section's Width box, put the actual width of the piece in.

Click OK.

Now, open the same Image Size window again. This time, check the Resample Image box, and UNcheck the Constrain Proportions box.

In the Document Size section's Height box, put in the actual height of the piece.

Click OK.

Save the file by clicking File and Save As. In the Format box, specify TIFF. Select an appropriate file name and location and click OK.

Congratulations. You've done it!

final image, with correct colors and correct proportions

File Size

A few more tidbits we need to discuss

How will you be using this digital file? Will it be for displaying on the Web or for print? Will it be distributed on a CD? Will it be incorporated in a presentation of some kind?

There are two fundamental classes of digital images: those intended for display on a computer and those intended to be printed. For print you need a much higher-resolution file.

For computer display, you only need it to contain as many pixels as the screen on which it will be displayed, no matter how large that screen is. A common resolution for computer screens these days is 1024 pixels across by 768 pixels high. (Note that computer screens are always in horizontal format.) If you're going to be giving a lecture in a giant hall with an enormous projection system connected to a computer, chances are that the resolution of the projector is still no more than 1024 by 768. But, find out!

Ok, here's a test, to find out if you've been paying attention:

We want to save the picture we've just been working on for display on a computer screen. Which of the following should we make it? (dimensions are width x height)

a 1024 x 768
b 768 x 1024
c 654 x 768

The answer is c, 654 x 768, because the picture is vertically oriented, so it won't fill the entire horizontal area of the screen, and the maximum height on the screen is 768 pixels. So we make the height fit and the width is what it has to be to maintain the correct proportions. Don't worry: you don't have to do the math.

If you're saving the file for some specific application, find out what the requirements are. If you just want to have a high-quality digital image, stick with the original size.

File Format

How will you be using this image?

You always want a TIFF (or PSD) version of your file, but if you're going to display the image on a computer, also save in the JPEG format, for that application. If you're saving for print, stick with TIFF. These formats are options that you can select when you click File and Save As.

A note about JPEG: This format compresses the data, and you lose some quality in the process. If you may have to make any changes and resave the file, do not use JPEG, or be sure to save a TIFF version as well. Each time you resave in JPEG format, you run the risk of losing more information.

You have already saved the full-resolution image as a TIFF file. If you now also want a version for viewing on a computer, you will want to lower the resolution and resave as a JPEG file. Go into Image and Image Size (again), check the Resample Image box and the Constrain Proportions box...

... and resize the image using the Pixel Dimensions boxes at the top of the window. Remember the limitations of your computer display (discussed above), or specifications for your particular application. (Notice that when you change either the width or height, Photoshop will automatically change the other, because you have told Photoshop to constrain the proportions.)

Then go to File and Save As. Be sure to do Save AS, and change the format to JPEG.

This illustration shows changing from TIFF to JPEG format. The extension on the file name will change from ".tif" to ".jpg" when you do that.

 

Presentation

How are you presenting your art work?

You can put your work into a slide show in a program like Microsoft PowerPoint, or you can put it in a gallery on a Web site. Or you can put it in an HTML-based presentation on a CD. Or you can just put the files on a CD (probably in JPEG format, for on-screen viewing).

If you're preparing for a specific purpose, find out what's expected. If you want the most flexibility, just put the files on a CD in JPEG format, in screen resolution, and keep your full-resolution, TIFF files elsewhere.

Again, if you are preparing for a specific purpose, find out what's expected!

End

I hope you've found this tutorial helpful.

R.L. Geyer