Resolution - Resolving power

It refers to the ability of a recorded image to reproduce the fine structure of the original image; resolution and resolving power are synonyms. It is expressed as the highest number of distinguishable parallel lines per mm. In the case of photographic images, it is determined by the combined resolving power of the optical system and the resolving power of the photosensitive material. The general method of determining resolution is to photograph a test chart with multiple levels of black and white parallel lines and determine the number of distinguishable parallel lines, but care must be taken as it is affected by the shooting and processing conditions. The resolving power of a lens is inversely proportional to the brightness ( F -number) and the wavelength (λ) of the light used; for an ideal, aberration-free lens, when F = 1.8 and λ = 365 nm, it is approximately 1500 lines/mm. The resolving power of photosensitive materials is determined by the particle size of the image-forming substance, the exposure conditions, and the processing conditions. With silver halide photographic materials, the higher the sensitivity, the smaller the maximum resolving power generally is. Resolution is a measure of "sharpness," which indicates the clarity of a photographic image's contours and the ability to depict fine details, but it may not coincide with the actual sharpness observed with the naked eye. This is because resolution is determined in the high spatial frequency range, and is unrelated to the low spatial frequency range that relates to sharpness. A more quantitative evaluation method is the MTF (modulation transfer function), which expresses the relationship between the light intensity distribution input to the meter being measured and the output (photographic density) for each frequency.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

記録画像が原像の微細構造を再現する能力をいい，解像性，分解能も同意語である．1 mm 当たり識別可能な最高の平行線数で表示される．写真像の場合には，光学系の解像力と感光材料の解像力の総合で決定される．解像力の決定には，多段階の黒白の平行線をもつテストチャートの撮影により，識別可能な平行線数を求めるのが一般的方法であるが，撮影や処理条件の影響を受けるので注意しなければならない．レンズの解像力は，明るさ(F値)と用いる光の波長(λ)に逆比例し，無収差の理想レンズでF ＝ 1.8，λ ＝ 365 nm のとき約1500本/mm になる．感光材料の解像力は像形成物質の粒度，露出条件，処理条件で規定される．ハロゲン化銀写真材料では，一般に高感度のものほど最大解像力は小さい．解像力は，写真画像輪郭の明瞭さと微細像描写能力を表す“鮮鋭度”を評価する一つの尺度であるが，実際に肉眼で観察したときの鮮鋭度とは一致しない場合もある．解像力は空間周波数の高い領域で決められ，鮮鋭度に関係する低い空間周波数領域には無関係なためである．より定量的な評価法として，被測定計に入力される光強度分布と出力(写真濃度)との関係を各周波数について表現したMTF(modulation transfer funcition：変調伝達関数)が用いられる．

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