The first photo is from Jessica's on-screen debut, during her show-stopping performance at the Ink and Paint Club. A point that might have gone unnoticed to the audience is that the Ink and Paint Club was based on real clubs of the 1940's. The Cotton Club was one such real establishment, where African Americans were not allowed in as patrons, but could be performers. This was a small undertone in the movie, but we can get the idea that the Toons were not treated equally to humans.
Comic Con 2013. Her strapless dress with thigh-high slit and opera gloves are used for Jessica's own costume. Veronica Lake's signature peek-a-book hairstyle, which covered one eye, became Jessica's familiar look. The Tex Avery cartoons of Red Hot Riding Hood were the basis for Jessica's design and performance at the Ink and Paint Club.
While the production photo above shows a woman in the place of Jessica Rabbit on set of the Ink and Paint Club scene, she was only used as a guide for the actors and extras to train where their eyes need to be looking at certain points of actual filming. When the routine was down, the scene was filmed without the woman - and it was up to the actors to remember where during the performance there eyes needed to be. It's a risky way of filming a movie, but no woman's proportions would match that of Jessica's, however, the animators did not want to be accused of simply drawing over a woman to achieve the effect anyway.
Jessica Rabbit was such an important character to the film that she had her own drawing class. In the above photos you can see drawing instructor Walt Stanchfield directing a model to walk and move like Jessica - while the artists do their sketch work. All these pieces came together to get Jessica's on-screen performance looking superb. It's one of the key moments of Who Framed Roger Rabbit and definitely memorable for all of film history. Take a look at the video below for Rita Hayworth's performance in Gilda - the look that inspired Jessica's creation.