• Cropped film still from the 1938 film Bringing Up Baby, featuring Katharine Hepburn and Cary Grant.
• Such images were taken on set during filming, or as part of an organized photo-shoot, by a studio photographer. They were then disseminated to the media and the public to promote the film. (see Film still)
• This is definitely a production still rather than a screenshot as the quailty is too high (compare, for instance, with this image, taken from the film's trailer).

Public domain explanation

• The full image (seen here) does not contain the copyright symbol ©, the word "Copyright", or the abbreviation "Copr.", as then required for copyright.
• Although it is possible that the above scan does not show the entire image, other Bringing Up Baby films stills where a stock number can be seen do not contain the copyright symbol ©, the word "Copyright", or the abbreviation "Copr.": [1] [2] [3] [4] [5] [6]. This suggests that no such images were issued with a copyright notice.
• By publishing a photograph without such a notice, under the terms of the 1909 Copyright Act (which was law until 1978) the image went into the public domain.
• If there is any chance that the photograph was copyrighted, under the terms of the 1909 Copyright Act it would have had to be renewed 28 years after publication. A search for copyright renewal records of 1965 and 1966 ([7], [8], [9], [10]) reveals no evidence that the then corporate heir to the corporate author of the work--RKO General--renewed copyrights to this photograph, as would have been required to maintain copyright protection, if any.

Film industry author Gerald Mast has written:

"According to the old copyright act, such production stills were not automatically copyrighted as part of the film and required separate copyrights as photographic stills ... Most studios have never bothered to copyright these stills because they were happy to see them pass into the public domain, to be used by as many people in as many publications as possible." (Film Study and the Copyright Law (1989) p. 87.)