I am sorry, but your picture would not download. The following response is from another expert's reply in Multnomah County to the same type problem.
A Cotinus is indeed a shrub and not a tree, though most of the ones you'll see are trained to look like a tree with two or three branches acting as the 'trunk' and the foliage as the canopy. You don't have to prune them like this, you can also prune them hard in Spring time and they will produce an abundance of fresh foliage and look more like a shrub. However if you choose this option you run the risk of missing out on the smoke-like flowers that Cotinus produces.
I did find this guideline to pruning Cotinus.

• 
  Left to develop with no interference from the gardener, cotinus naturally grows as a very large shrub, reaching 15 ft. or more, high and wide, arching to the ground.
• Left unpruned, the form is more accurately a very large shrub rather than a tree.
• Because cotinus is amenable to sculpting, it’s possible to create a smaller shrub or a small tree.
• Once pruning has commenced, however, it must continue annually to maintain the desired shape; otherwise, smoke tree will revert to its natural growth habit, spreading high and wide.

Small Tree

• To create a single- or multi-trunked tree, wait until the plant has been in the ground for 2-3 years, then begin to limb up the shrub.
• Select one to three stems that will become the single or multiple trunks and remove lower branches.
• Continue to shape this way until you arrive at a satisfying tree-like shape over a period of 2-3 years.
• You may need to remove lower and interior branches that appear annually.
• If very tall shoots appear, unless removed, they will eventually arch horizontally and revert to a shrub form. Once removed, they will continue to re-grow annually.

Large Shrub

With no pruning after planting, cotinus naturally assumes the form of a very large shrub, 10-15 ft. high and wide.

• To form a smaller, globe-like bush, every year in late winter or early spring before bud break, cut all stems to 6-12 in. above the ground.
• The result will be large, colored foliage at eye level for easy viewing, but no smoke-like flowers will appear.
• Cotinus blooms only on branches at least a year old, all of which are removed by annual pruning.
• By pruning severely every other year, the plant will still be at manageable size and flowers will bloom on untrimmed branches.
• Pruning is done from late winter to very early spring.