Advanced Imaging


Advanced Imaging Magazine

Updated: January 12th, 2011 10:01 AM CDT

The Wonderful World of Color

When is it worthwhile to purchase a color MV camera?
Ripeness Check of Products
Color machine vision allows inspectors to check for ripeness and product quality
Single-chip area scan
Toshiba Imaging Systems
Fig. 2: Single-chip area scan cameras use a single sensor that is covered by a color filter with a fixed, repetitive pattern. To reconstruct a complete color image the red, green and blue information is interpolated across several adjacent cells to determine the total color content of each individual cell.
3CCD Cameras
Toshiba Imaging Systems
Fig. 3: 3CCD cameras contain three image sensors and a prism that divides the incoming light rays into their red, green, and blue components. Each chip then receives a single color at full resolution.
JAI’s CV-M9 GE camera
JAI’s CV-M9 GE camera is based on 3CCD prism technology, but has a GigE Vision interface.

By Barry Hochfelder

Toshiba’s line of seven camera-link and analog 3-chip cameras include its latest, the IK-TF9C, which uses a camera-link interface. The model features a 2048 x 1536 pixel output resolution with a frame rate of 20 frames per second in full frame and 40fps in partial scan. Its IK-TU51 remote head camera has been integrated into Apollo Telemedicine’s ASAP Imaging® telediagnostic medical imaging software, which allows a pathologist to look at real-time high-resolution images from under a microscope via internet streaming video.

DALSA expanded its Piranha family of line scan cameras to include a Piranha Color model. DALSA’s tri-linear sensor technology uses three sensors on one die - one for each color, red, green, and blue, and achieves three-pixel center-to-center line spacing. The Piranha Color has a camera-link interface and is available in 2k or 4k resolutions with line rates up to 33 kHz, allowing users to inspect more material in less time.

A new entry in the 3CCD category is JAI’s CV-M9 GE camera which, unlike others, has a GigE Vision interface. It also features programmable general purpose input/output ports (GPIO) and uses Cat5e or Cat6 cabling and doesn’t require a dedicated frame grabber in the PC.


Color isn’t necessary if you want to inspect your product for scratches or bumps on its color finish. Why? “In this instance the defects disrupt the evenness of a surface, which in turn affects the way light is reflected,” says DALSA’s Howison. “When you’re grabbing images of a homogeneous surface (one that’s perfect and has no discernable texture) all the pixels in the image will be about the same. But as soon as you grab an image of a scratch or a bump, suddenly light gets scattered in different directions. The scratches and bumps create areas of pixels that are darker and lighter, which means you don’t need color.”

When do you need color? “Any time you need to evaluate the presence or density of a color, its evenness of distribution or its similarity to some known reference,” Howison says. One example is food. “Color allows us to determine ripeness and grade product quality. In the case of grains and legumes, color helps to grade product quality and distinguish foreign matter in a steady stream of product. In meat processing, color can be used to detect spoilage and discriminate areas of fat, bone and gristle for automatic trimming.”

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