Apple's expert witnesses once again took up much of the court's time Tuesday in the Cupertino company's ongoing suit against Samsung, though the latter's legal team made a characteristic splash early.

In a case of the pot calling the kettle black, Samsung's lawyers accused Apple's counsel of tampering with evidence, specifically tweaking the layout of a Samsung phone to make it look more like an iPhone.

Samsung said a photo of an Epic Touch 4G's icon layout that looked similar to that of the iPhone didn't look like an out-of-the-box Epic.

To prove their point, Samsung's team presented its own photo showing a different layout with a large number of homescreens, a photo they claimed was taken Sunday night.

Caught in the act

Lucy Koh, the perpetually harried U.S. District judge presiding over the trial, took aim at Samsung, questioning whether it wasn't Samsung's phone that was the fake.

Koh pointed out that Samsung's Epic photo didn't feature the Google search widget, a feature Samsung attorneys said was present on the phone out of box.

She also noted the date on the screen in the image read Monday's date, not Sunday's as the team said. The Samsung attorney who made the claim admitted he misspoke.

Apple, naturally, denied any manipulation. Koh deemed Apple's claims credible, telling Samsung lawyers she didn't "believe [their] story" and ruled that both parties will have to agree together in advance of any images used for joint exhibits.

"I'm not going to have this happen again," she warned.

What is 'substantially similar'?

Peter Bressler, a product design expert brought in as an Apple witness - with a running tab of $400 an hour - was the first witness up as he finished testimony he began Monday.

After a few softball questions from Apple, Samsung attorney Charles Verhoeven "recrossed" the man who holds about 70 patents, circling back to a statement Bressler made yesterday that the design of Apple's devices and some of Samsung's are "substantially similar."

Judge Koh: "I'm not going to have this happen again"

Their discussion seemed to go nowhere and Verhoeven let Bressler go, though not without the witness walking away with $75,000 from Apple.

'Macintosh artist' takes stand

Susan Kare, a designer who was part of the early Macintosh team and a former Next employee, followed Bressler.

Kare, who described herself as a "Macintosh artist," designed classic icons like the "happy Mac" startup graphic, the lasso and paint bucket icons and Chicago and Geneva fonts as well as Facebook's Gifts icons.

When asked by Apple's lawyers if she drew conclusions that Samsung's phone display screen designs produce the same overall visual impression as the iPhone's, Kare answered "yes."

Picking apart specific phones, Kare, dubbed the "Betsy Ross of PC," said Samsung's Fascinate is "substantially similar" to the iPhone patent because of its grid, four rows of icons and colorful mix of square icons.

She said the "overall visual impression" of Samsung's Captivate, Continuum, Droid Charge, Epic 4G, Galaxy S 4G, Galaxy S (i9000), Gem, Indulge, Infuse 4G, Mesmerize, Vibrant and Galaxy S Showcase is the same as the iPhone.

As part of research she conducted for Apple's trade dress claims, Kare said she also found that in a set of 11 Samsung screens, she found the overall visual impressions were "confusingly similar" to the original iPhone.

Why did Kare reach this conclusion?

"The overall collection of graphic features…could be confusing to a consumer," she said.

She'd go as far as to say Samsung's device designs "were beyond coincidental."

"It seemed likely to me that Samsung used iPhone screen graphics as a guide," she said.

As a comparison to see if comparable phones could be designed differently, Kare said she reviewed the BlackBerry Torch.

While similar products in terms of functionality, Kare found the designs different enough not to create customer confusion.