SAN JOSE, Calif. –  Samsung Electronics Co. moved Tuesday from attacking the validity of Apple’s intellectual property to claiming the iPhone maker infringes Samsung patents in a trial in San Jose, California.

Samsung made the tactical shift on the second day of presenting its case, in the third week of trial, by calling Woodward Yang, a professor of electrical engineering at Harvard University, who testified that versions of Apple’s (Nasdaq: AAPL) iPhone, iPod and iPad infringe three Samsung patents.

Yang focused on one patent that allows a user to send an e- mail with photographs contained in the messages. The patent also covers the function of scrolling through photographs, he testified. Yang pointed to Apple’s iPhone 3G, iPhone 3GS, iPod Touch fourth generation, and the iPad2 as infringing products.

Apple products also infringe a third Samsung patent, one covering methods used in mobile devices to play MP3 music files, the engineering professor said.

Yang followed testimony of two computer scientists Monday called by Samsung to attack Apple’s claimed originality of its software patents at issue in the multibillion-dollar trial in California.

No Originality

The witnesses demonstrated technologies resembling and predating Apple’s “rubberbanding” — the way an iPad or iPhone screen seems to bounce when a user scrolls to the end of a file — years before the 2007 release of the iPhone.

Benjamin Bederson, a University of Maryland professor, told jurors about his “Launch Tile” invention, a system of 36 tiles, or application icons, in an interface allowing users to zoom in and out and interact with the images. A “snapback feature” permits a user to scroll through the images until the border of the last tile is reached, when it stops. Jurors were shown a video of the program, released in 2004, demonstrated on Hewlett-Packard Co.’s HPiPAQ 1900 pocket personal computer.

“Users don’t have high precision when they’re using this kind of device,” he testified. “This way they only have to get nearby and the system will take them where they want to go.”

Samsung began putting on its case after Apple concluded its presentation of testimony that started July 31. Apple, based in Cupertino, California, sued Suwon, South Korea-based Samsung in April 2011, accusing it of copying patented designs. The dispute is the first to go before a federal jury in a battle being waged on four continents for dominance in a smartphone market valued by Bloomberg Industries at $219.1 billion.

Second Witness

Samsung’s second witness, Adam Bogue, president of Circle Twelve, based in Framingham, Massachusetts, testified about his 2001 Diamond Touch, a table of projected images that can be manipulated with one’s hands. Adding the “table cloth” technology he first demonstrated in 2005 allows a user to pull the projected table back, grab an item and let it “snap back” into position, he said.

The testimony was aimed at countering a series of witnesses Apple called over the last two weeks to try to show that Samsung has copied the design and technology of its iPhone and iPad. Samsung’s lawyers have sought in cross-examination to undermine Apple’s testimony by demonstrating that its own smartphones and tables evolved through competition rather than mimicry.

Apple’s witnesses included its director of patent licensing and strategy, Boris Teksler, who testified that the company’s late co-founder, Steve Jobs, confronted Samsung executives in 2010 after they introduced the Galaxy smartphone and that Apple warned against copying the iPhone. Teksler told the jury yesterday that Apple had an “anti-cloning” agreement with Microsoft Corp.

Paid Experts

The jury also heard from paid expert witnesses who claimed that Samsung copied Apple design features like the rounded rectangular body of the iPhone and functions such as “rubberbanding,” the way an iPad or iPhone screen seems to bounce when a user scrolls to the end of a file.

An October 2010 Apple document introduced as a court exhibit last week showed the company was proposing that Samsung license its patent portfolio for $30 per smartphone and $40 per tablet.

In addition to patent infringement, Apple contends that Samsung’s copying of the look of the iPhone and iPad has diluted the value of its iconic brands.

Apple used market survey research to try to show the jury that Samsung has copied its devices so closely that a consumer seeing products made by the South Korean company would actually believe them to be made by Apple. Samsung sought to demonstrate there is little actual confusion among consumers between its and Apple’s products.

Certified Accountant

Apple’s final witness, a certified public accountant, testified yesterday that Samsung would owe at least $2.5 billion in damages for infringement. He said his estimate is based on Samsung’s sales of 22.7 million allegedly infringing smartphones and tablet computers and revenue of $8.16 billion, starting when the Galaxy devices were introduced in June 2010.

Beyond its claims for damages, Apple wants to make permanent a preliminary ban it won on U.S. sales of a Samsung tablet, and extend the ban to Samsung smartphones.

U.S. District Judge Lucy Koh has limited each side to 25 hours to present their cases.

After Apple rested, Koh granted a request by Samsung to exclude infringement claims related to three of its phones – the Galaxy S i9000, the Galaxy Ace and the Galaxy S II i9100 – on grounds that they weren’t manufactured to be exclusively sold in the U.S.

Apple’s claims remain intact against more than 20 other Samsung devices.

The case is Apple Inc. v. Samsung Electronics Co. Ltd., 11- cv-01846, U.S. District Court, Northern District of California (San Jose).