Yesterday may not have been the best day in court for Apple, but Cupertino rebounded today, calling several witnesses that were able to effectively argue its case — while Samsung received another slap from Judge Lucy Koh.

Samsung began the day by accusing Apple of tampering with one of the joint exhibits — an Epic Touch 4G — to make its icon layout look more like the iPhone. Samsung claimed to have learned of the issue over the weekend, and presented an alternative picture it said was taken Sunday night. Unfortunately, the date on the image indicated it had been snapped Monday instead. Getting increasingly frustrated, Koh finally told Samsung "I find it not credible that Apple tampered with these phones," overruling the objection.

Icon designer Susan Kare then took the stand for Apple. A veteran of the original Macintosh team, Kare walked the jury through her evaluation of Apple's icon design patent and trade dress claims — and how the accused Samsung phones compared. "I concluded that this set of screens... compared with the iPhone 3G, were confusingly similar," she said.

The Fascinate reflected an iPhone influence

In response, Samsung attorney Charles Verhoeven attempted the same strategy that worked so well yesterday: take things down to a microscopic level of granularity in an effort to discredit the witness or lose the overall point in the weeds. Kare seemed to hold up well, however, repeatedly stating that her mission was to address the "overall visual impression" that the devices gave. Samsung's own Galaxy S evaluation documents also made another appearance, providing Kare the opportunity to point out icon changes made before the phone shipped on Verizon as the Fascinate — changes that seemed to reflect an iPhone influence.

A large part of Apple's case depends on whether the company can prove that the iPhone and iPad had become recognizable products in their own right, and that Samsung diluted that brand power with its devices. To that end, Apple rounded out the day by calling Dr. Russel Winer and Hal Poret. Winer had prepared a report on the "blurring" of the iPhone and iPad; essentially, on whether customer confusion existed due to Samsung products (he felt it did). Samsung was quick to question Winer's conclusions, however, noting that he'd collected no hard data to back up his claims.

Samsung's favorite kind of courtroom theatrics: the startup sequence

To make the point that prospective customers wouldn't be confused, Verhoeven turned to what's proving to be his favorite kind of courtroom theatrics: the startup sequence. He put the Galaxy Tab 10.1 beneath an overhead projector and showed the jury the Samsung logo the user sees at startup (he's done the same with one of Samsung's phones and the iPhone at this point). Of course, whether customers planning to buy a device would every see a startup screen at a store is a different question entirely.

Hal Poret proved to be a bit of a surprise. Appearing mild-mannered and reserved at first, Poret described surveys he'd conducted to assess how strongly consumers associate the look of the iPhone and iPad 2 with Apple; the iPad in particular scored quite well in his findings. When pushed by Samsung attorney Bill Price on his methodology, however, Poret became exasperated by what he felt were "arbitrary" assertions, finally telling Price "I can tell you're confused."

Poret will wrap up his testimony on Friday when the trial resumes, with several other expert witnesses for Apple scheduled to follow. We'll be there as the story continues.