The photo shows them sitting on a bench.

It shows Sandy watching Tv.

The photograph showed him wearing football togs.

照片上显示的是一个场景，或者说捕捉了一个画面。该场景或画面中某人在做某事，而不是做某事的某个人。所以可以排除现在分词作定语。

记得我曾和刘老师讨论过show后面的sb doing sth究竟是动名词复合结构作单宾语，还是宾语加现在分词作宾补，为复合宾语。现在看来，刘老师的观点是正确的，这个结构应该是现在分词作宾补。理由是，这个句子可以改为被动句，sb is shown doing sth. 只有复合宾语结构才可以改为被动句，用宾语作主语，宾补保留，改称主语补足语。动名词复合结构或现在分词作定语都不能这样改为被动句的。

以下为COCA类似被动句结构，提示主动句时，现在分词为宾补。

The Bengals have been criticized for using the 48th overall draft pick on Mixon,

who was shown on camera punching a woman in the face and fracturing her jaw during his freshman year at Oklahoma in 2014.

Jackson had said of the star, who was shown quickly cozying up to his affections.

The researchers found that 10-month-olds also reached this conclusion: When the agent was shown choosing the first goal, infants looked at the scene longer, indicating that they were surprised by that outcome.

She was shown falling off a chair while meeting Dr. Oz in the episode.