An Optical Mixer and RGB Control for Fine Images using Grey Scale Distribution

Cho

Proceedings of the 2013 IEEE/SICE International Symposium on System Integration

et al. 2013

This study proposed how to find optimal illumination for industrial vision in short time using random search algorithm and multiple color light sources. The fineness of an image captured by a monochrome camera is varied by illumination and can be evaluated by image sharpness. The relation between the sharpness and the illumination is nonlinear, so direct optimum methods are applicable to mix the multiple sources. Random search is one of the direct optimum methods and were derived from the sharpness as input and N driving voltages for N light sources. The random search was tested in an RGB mixer and reduced the number of iteration for optimal illumination compared with conventional equal step search.

“…The optical mixer was constructed in our former research. [12]. The mixed had three voltage inputs for RGB LEDS and the driving current was adjusted by the inputs.…”

Section: B Random Searchmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Color mixing and random search for optimal illumination in machine vision

Cho

Proceedings of the 2013 IEEE/SICE International Symposium on System Integration

et al. 2013

“…Hence, the light color is important in the manufacturing process, but the color selection is mostly limited at the hardware level of a light source. A mixed light source can generate various colors by combining RGB LEDs, and it is constructed by using an optical mixer such as a collimator [4] , micro-lens array [5] , shell mixer [6] , diffuser [7] , or bundle of optical fibers [8] . Although such a mixed light source can generate various colors, the spectral ranges of high-power LEDs are constant.…”

Section: Introductionmentioning

confidence: 99%

Generating selected color using RGB, auxiliary lights, and simplex search

International Journal of Optomechatronics

et al. 2016

Self Cite

A mixed light source generates various colors with the potential to adjust the intensities of multiple LEDs, which makes it possible to generate arbitrary colors. Currently, PCs and OSs provide color selection windows that can obtain the red, green, and blue (RGB) or hue, saturation, and lightness (HSL) color coordinates of a user's selection. Mixed light sources are usually composed of primary-colored LEDs with LEDs in auxiliary colors such as white and yellow used in a few cases. The number of LED inputs and the dimming levels are greater than the number of elements in the color coordinate when using auxiliary-colored LEDs, which causes an underdetermined problem. This study proposes a method to determine the dimming levels of LEDs based on a simplex search method (SSM). Commercial LEDs have different optical power values and impure color elements, even if they are RGB. Hence, the characteristics of the LEDs were described using a linear model derived from the tri-stimulus values (an XYZ color coordinate model) and dimming levels. Color mixing models were derived for an arbitrary number of auxiliary-colored LEDs. The underdetermined problem was solved using an SSM without an inverse matrix operation. The proposed method can be applied to a machine vision system and an RGBW light mixer for semiconductor inspection. The dimming levels, obtained using the proposed method showed better optical responses than those derived using other methods.

“…A mixed light source can generate various colors by combining RGB LEDs and is constructed using an optical mixer such as a collimator, [4] micro-lens array, [5] shell mixer, [6] diffuser, [7] or bundle of optical fibers. [8] Although such a mixed light source can generate various colors, the spectral ranges of highpower LEDs are constant. Therefore, auxiliary color LEDs are applied to a mixed light source when spectral-range flexibility is required.…”

Section: Introductionmentioning

confidence: 99%

Generating Selected Color using RGB, Auxiliary Lights, and Simplex Search

MATEC Web of Conferences

et al. 2015

Abstract. A mixed light source generates various colors, with the potential to adjust intensities of multiple LEDs, which makes it possible to generate arbitrary colors. Currently, PCs and OSs provide color selection windows that can obtain the RGB or HSL color coordinates of a user's selection. Mixed light sources are usually composed of LEDs in the primary colors, with LEDs in auxiliary colors such as white and yellow used in a few cases. When using auxiliary color LEDs, the number of LED inputs, the dimming levels, is larger than the number of elements in the color coordinate, which causes an under-determined problem. This study proposed how to determine the dimming levels of LEDs based on the selected color. Commercial LEDs have different optical power values and impure color coordinates, even if they are RGB. Hence, the characteristics of the LEDs were described using a linear model derived from the tri-stimulus values (an XYZ color coordinate model) and dimming levels. Color mixing models were derived for the arbitrary number of auxiliary color LEDs. The under-determined problem was solved using a simplex search method without an inverse matrix operation. The proposed method can be applied to a machine vision system and an RGBW light mixer for semiconductor inspection. The dimming levels, obtained using the proposed method were better than derived using other methods.