Senator Cooper. On that point, would it require study to learn to make, to exercise these techniques, either from a textbook or information from someone else or by observation of the practice?
Mr. Cole. I think observation and association with other people, or being in a place where such techniques were going along in the normal operation of a photographic laboratory or printing plant, would be enough. A person wouldn't have to consult a text. As a matter of fact, similar things are done for normal printing operations.
Senator Cooper. That is the question I wanted to ask. Would this type of technique in an average shop or plant be normal?
Mr. Cole. Oh, yes.
Senator Cooper. Would it require much practice on the part of an individual before such technique could be successfully accomplished?
Mr. Cole. No; I would say a moderate amount of practice.
Senator Cooper. How much, would you say? How many times would a person have to, if it is possible to say, practice this kind of a technique before he could do it reasonably well?
Mr. Cole. On a trial-and-error basis. I would say that a half dozen attempts on a trial and error basis of going through such an operation, perhaps making an error, finding how to correct it, doing it again, achieving more success, would certainly be enough.
Senator Cooper. You would say then, assuming that Lee Oswald made these changes, that he would have had to practice them several times before he could have successfully made the changes which were indicated by the exhibits that have been introduced?
Mr. Cole. Well, sir; I would say he would not necessarily have to practice on this particular document, but if he had some practice, he or any other person, had had some practice in normal operation, similar operations in a printing plant, then he could accomplish this result.