Category: aspect ratio

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What went wrong?

Photoshop is a great tool for figuring out how to fix a painting.

Surf at Marshall Point, by Carol L. Douglas
Yesterday I painted at Marshall Point. I was with Barbara Carr, who comes to Camden just once a year. My intention wasn’t to create a masterpiece, but to spend a few hours painting with a friend.
Marshall Point has a beautiful lighthouse, which made a cameo appearance in the movie Forrest Gump. As lovely as it is, I never paint it. I’m always mesmerized by the surf and the light on the sea.
My sketch for the above.
Barbara is an experienced painter, with a BFA from Massachusetts College of Art and a lot of years of practice under her belt. Still, I must be very tired. I’m usually a fast painter, but she finished two fine paintings in the time I painted one.
Our tides may not be Bay of Fundy class, but we still have high and strong tides here in mid-coast Maine. That means the rocks are uncovered fast in an ebb tide and covered equally quickly in a flood tide. The only answer to this is to draw fast and then use other rocks to fill in the details. In general, this strategy allows a lot of latitude for design, providing the artist is fully awake.
Lightening the foreground rocks did not help.
I liked what I did well enough when we were on site, but was ambivalent when I got it home. Comparing it to my sketch, I noticed two things. I had centered the large rock slightly compared to my original composition. The foreground in my sketch was darker than I’d originally proposed.
Adobe Photoshop or a similar graphics editor can be a useful tool for pondering possible revisions. I lightened the foreground rocks to see if that would help. That left a dark rock sitting in a sea of blue—factually true, but hardly interesting.
Cropping helped a little, but not enough to redeem the painting.
Generally, plein airpainters use prepared boards in standard sizes. That means we’re at the mercy of canvas and frame makers in determining our aspect ratio.  (The alternative, customizing both frames and boards, is just too much work.) “Aspect ratio” just means the proportional relationship between the canvas’ width and height.  A 9X12 canvas, for example, has an aspect ratio of 3:4, making it exactly the same shape as a 12X16 canvas.
Of course, the sketch in my sketchbook is often a very different aspect ratio. If I’m not careful—and I wasn’t—I can relocate things to where they don’t belong when I transfer my idea to a larger board.
Common canvas shapes.
I cropped my image to see if moving the rock more to the right would help. Again, I don’t think it made much difference.
The real issues are more fundamental: the rocks and the waves are resolutely parallel to the picture frame, and all the action is below the mid-line. Another rock, middle-right, will do this painting a world of good. So will tightening up the edges of the waves. Those are easy fixes. I can do them in my sleep, and possibly will.
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How to scale up a small sketch to a large painting

A large canvas transferred from a 9X12 sketch.
When working on a very large canvas in a normal-size room, I start with a smaller sketch (either in oil or graphite) and scale it up. There just isn’t enough space to stand back far enough to draw directly on the canvas.

I realize many artists are math-phobic, but there are times when an eensy-weensie bit of arithmetic can save  you a lot of work. I’ll try to make this painless.

The first step is to work out whether the aspect ratio of the sketch is the same as the canvas. This is the proportional relationship between height and width.
Usually I grid in Photoshop because it’s faster and I can just delete the lines with a keystroke. But you can grid just as well with a pencil on your sketch.
Sometimes this is very obvious, such as a 9X12 sketch being the same aspect ratio as an 18X24 canvas. But sometimes, you’re starting with a peculiar little sketch drawn on the back of an envelope or something. You can use a trick you learned back in elementary school.
Remember learning that ½ was the same as 2/4? We want to force our sketch into a similar equivalent ratio with our canvas.
Let’s assume that you’ve cropped your sketch to be 8” across, and you want to know how tall your crop should be to match your canvas.
Write out the ratios of height to width as above.
To make them equivalent, you cross-multiply the two fixed numbers, and divide by the other fixed number, as below:
Use your common sense here. If it doesn’t look like they should be equal, you probably made a mistake. And you can work from a known height as easily as from a known width; it doesn’t matter if the variable is on the top or the bottom, the principle is the same.
The next step is to grid both the canvas and sketch. You could spend a lot of time calculating the distances, but I prefer to just divide it in quarters in each direction. I use a t-square and charcoal, and I’m not crazy about the lines being perfect; I adjust constantly as I go.
This was gridded in eighths instead of quarters because I wanted to be sure I got the water in the bottom right in the correct spot. But usually, I just divide the canvas in quarters in each direction.
The last step is to transfer the little drawing, square by square to the larger canvas. I generally do this with loose paint, in raw umber. It’s time-consuming, but with big paintings it saves a lot of work in the long run.

Let me know if you’re interested in painting with me in Maine in 2014 or Rochester at any time. Click here for more information on my Maine workshops!