1）Simultaneous color contrast by different devices 

 One of the well-known phenomena of chromatic adaptation is “Simultaneous color contrast”.
 Many researchers described the phenomenon as the gray test stimulus influenced by the color of
 surrounding field and effected to the perceive the gray test stimulus slightly colored depending
 on the color of surrounding. For example, the gray patch when it is surrounded by a green field
 appears slightly reddish. In the present work we demonstrate different effect of the simultaneous
 color contrast depending on devices; a display, colored object, and colored object covered by a tissue.
 A gray patch of the sized 3x3 cm2 was placed on a colored background at its center. the display case a
 commercially available unit was used and for the two-room technique an experimental booth was
 constructed, which was composed of two rooms, a subject room and a test room connected by a
 separating wall on which a small window was opened through which a subject could see a white board
 placed in the test room from the subject room. The small window worked as the central gray patch.
 The color and the luminance of the surrounding were adjusted about same for both cases. Subject’s
 task was to judge the color appearance of the central gray patch by the elementary color naming method,
 namely, to judge the amounts of chromaticness, whiteness, and blackness in percentage and amount of
 unique hues also in percentage. The result showed high amount of chromaticness of the gray patch
 in the two-room technique and display respectively. But on the contrary, in the object case it was
 very small even if any. These different effects of the simultaneous color contrast are explained by the
 concept of the recognized visual space of illumination RVSI which emphasizes the illumination for the
 chromatic adaptation. It was interesting to note a large effect of the simultaneous contrast with a tissue
 covering the object.

 
2）残像における同時色対比
Simultaneous color contrast in afterimage

小さいグレーのパッチを例えば赤で囲むとグレーがやや緑がかって見える。同時色対比と呼ばれている現象である。
しかしその緑は決して鮮やかでなく、あるかないかの色である。ところが延滞をしばらく見つめ、続いて白い面を見る
と残像が見える。残像の中のパッチはとても鮮やかな色に見える。残像の色対比は顕著である。
ここでは残像の色をelementary color naming法で測定残像の色を見るメカニズムを検討する。残像における色の見え
は2部屋法で見る色の見えと同じであることから、残像の色は大脳での現象であることを主張する。