Preservation of Photographs

Photogrophs ore susceptible to degradation (rom many sources. Attock on the imoge or bose can occur (rom residual processing chemicals. industrial atmospheric pollutants, contaminants (rom storage area construction materials or (rom the materials used (or mounting and containing the pictures. Degradation (rom poor processing can be detected with simple chemical tests. Until more becomes known about the many products normally associated with the preservation o( photographs, one should avoid using in the storage area fresh point, raw woods and volatile substances, and near or on the photographs avoid adhesives, plastics and poor quality papers. Regardless o( the preservation technique used it is help(ul to remember that the storage li(e of photographs can be extended by slowing down chemical activity. This can be achieved by care(ul control a( storage temperature and relative humidity (60 references).     

Photographs from Auschwitz

Abstract

Photographs, albums, families. Many psychotherapists ask their patients to bring in their family albums to discover a new, sharper point of view of the family, its structure and dependencies. Many times we ask friends to show us their family photo album to get to know them better. Sometimes we ourselves look at our own family photo album and all of a sudden we see details we have not yet noticed: a smile, a look, a sign.     

Walker Evans' American Photographs

Abstract

It is an article of faith among photographers and scholars that Walker Evans' American Photographs is a sequence of pictures rather than a simple collection or anthology; that is to say that the photographs should be looked at in the order in which they are given. Indeed the book is often spoken of as innovative and influential in precisely that respect (among others). Some years ago I set out to learn more about the origin of Evans' sequence in the context of a broader investigation of American Photographs.¹ That study (which remained unpublished) has now been superseded in many ways by Alan Trachtenberg's insightful discussion in the book Reading American Photographs, which appeared in 1989.² Nevertheless some of my original material remains useful and I offer it here largely intact, with only a small number of revisions and additions.     

Photographs in the Janos Scholz Collection

Abstract

Janos Scholz (1903–1993), who was to become one of the great cellists of the twentieth century, began collecting when he was a child in Sopron, Hungary. After completing his studies at the Royal Hungarian Academy of Music, Scholz was named first cellist with the Budapest Symphony Orchestra. In 1932 he joined the Roth Quartet, and the following year he left Hungary to tour with the quartet in the United States. He became an American citizen in 1933 and made his home in New York until his death in 1993. Scholz began to collect prints and drawings in 1935 and over the next three decades he amassed an unrivalled collection ofItalian drawings. In keeping with the nature of his life as a musician, in which he shared his music through public recitals, Scholz announced in 1973 that he had decided to give his drawings to the Pierpont Morgan Library in New York. Soon afterwards he began a new collection, one that focused upon nineteenth-century European photographs on paper.     

浅谈数码彩色照片的色彩管理

用数码照相机拍摄的画面所冲洗的彩色照片往往效果不能达到拍摄时在照相机储存卡上记录并在显示屏上看到的画面水平。产生这种差距的原因是多种多样的，本文对此进行分析。并对其中的一个重要方面：色彩管理，进行研究探讨，指出这主要是由于人眼对于色彩的感应能力的选择性，即所谓光谱灵敏度的特殊性所引起的。解决问题的关键就是使整个成像系统和过程都以人眼的光谱灵敏度为基准，并适度结合场景和人们的爱好进行全面控制，这就是色彩管理的任务。     

如何保持黑白照片长久不变色不褪色

黑白照片的影像，在长久保存期间，受外界的有害气体、空气、湿气、光和热的作用，会逐渐发生变化：变黄、变棕甚至褪色。本文详细阐述这些变化的原因、发生的化学反应，并提出了避免这种变化的措施。     

Optical Processing of Bubble Chamber Photographs

Purely optical methods of spatial pulse width coding for coherent optical densitometry are described. The proposed coding scheme correlates the image intensity with the orientation of one edge of triangular or trapezoidal pulses. One encoding technique employs a contact screen similar to those used for half-tone printing. The image to be coded is copied through this contact screen onto hard-limiting film. This method is limited to the encoding of images with density distributions varying only slowly across the area of one pulse. A holographic encoding technique overcomes these drawbacks, utilizing the storage redundancy of holograms recorded with diffuse object beams. An array of identical holograms is reconstructed with a beam spatially modulated by the image transparency to be encoded. The array of reconstructed real images is recorded on hard-limiting film and renders a pulse-modulated version of the original image. The limiting conditions for the pulse size and the size of details in the image imposed by diffraction effects and speckle pattern are derived.     

Degradation of Gelatin in Historical Photographs

Abstract

In order to study age related changes in photographic gelatin toe analysed black-and-white roll film before and after accelerated ageing and samples of naturally aged glass plate negatives. Two-dimensional gel electrophoresis (2D-PACE) was used to separate collagen chains In the gelatin by isoelectric point (pi) and molecular weight. The results shoiv that the x-chatns break down into smaller fragments on ageing. Amino acid analysis ivas performed to examine the oxidative deterioration of gelatin. It shows that the amount of lysine decreases with age.     

Preparation of Stereoscopic Electron Microscope Photographs

The author discusses some of the problems involved in the mounting of stereoscopic electron microscope photographs taken on 35mm film.     

The Translation of Colours into Black-and-White Photographs

Usual chromatic sensitization of black-and-white films attempts to translate a completely natural subject, rich in tone values and colours. into a monochrome representation. To remind an observer of the subject is only possible when taking both into account. A theoretical spectral sensitivity like that of the eye, neither at normal nor at increased contrast, is satisfactory in spite of the apparent obviousness of its choice, because the exact rendering of relative luminosities must be disturbed if objects of different hue, but of equal visual luminosity, are to be distinguished. The usual chromatic sensitivity of block-and-white films is sotisfactary; it might be improved further by slightly reducing the sensitivity to blue light, and increasing that to green light.     

怎样控制黑白照片的反差与影调

如今,在彩色摄影与数码摄影的夹击下,黑白摄影仍能顽强生存的重要原因之一,在于黑白照片可按创作意图去控制反差与层次(影调),使之具有独特的表现力,这也是手工放大无法被机械扩印替代的原因。黑白照片的反差与层次常常是一对矛盾——反差高则层次少;反差低则层次丰富。而反差高的照片看上去明快富有感染力,反差小的照片表现细腻,但感染力不如反差高的照片那么强烈。所以,对黑白照片反差、影调的取舍,要根据照片的题材、内容去决定。比如对人像选材,反差宜小一些,层次应丰富、细腻些。对人像选材中的老人或体力劳动者,反差可相对大一些,影调…     

牙齿形态图像的对比研究

在法庭科学中，人体鉴别主要采用下列四种技术：指纹鉴别、眼角膜纹识别、DNA技术和牙齿形态识别。指纹载体是综合性有机物，眼角膜是软组织，都不能长久保存，且我国未形成无前科人群的档案库，DNA技术虽精确，并已广泛应用，但费用昂贵而费时，因此这三种技术都有其不足之处。相比之下，牙齿形态鉴定法无上述缺点，效果甚佳。本文对此作了较详细的介绍。