Slope Control in Colour Printing

The prints produced by an automatic printer may vary systematically in density level and in colour balance as functions of the densities of the negatives. These variations are usually functions of reciprocity failure of the paper, and of spectral sensitivity-differences between paper and monitoring photocells. Slope control provides means for attaining high quality prints from negatives of widely differing densities in spite of inherent printer and paper limitations. The application of slope control to a particular printer is described.     

Printing colour at the optical diffraction limit

The highest possible resolution for printed colour images is determined by the diffraction limit of visible light. To achieve this limit, individual colour elements (or pixels) with a pitch of 250?nm are required, translating into printed images at a resolution of ～100,000 dots per inch (d.p.i.). However, methods for dispensing multiple colourants or fabricating structural colour through plasmonic structures have insufficient resolution and limited scalability. Here, we present a non-colourant method that achieves bright-field colour prints with resolutions up to the optical diffraction limit. Colour information is encoded in the dimensional parameters of metal nanostructures, so that tuning their plasmon resonance determines the colours of the individual pixels. Our colour-mapping strategy produces images with both sharp colour changes and fine tonal variations, is amenable to large-volume colour printing via nanoimprint lithography, and could be useful in making microimages for security, steganography, nanoscale optical filters and high-density spectrally encoded optical data storage.     

A High Speed Colour Printer

A high-speed printer for making colour paper prints from colour photographic negatives has been engineered and constructed by Technicolor Corporation. Salient features of the printer are: automatic operation; two printing beams; high production rate; preceding of negatives; stable operation. Special design features to attain fast, stable operation are incorporated.     

A Machine for High Speed Printing from 35mm Colour Transparencies

A machine for making colour prints at high speed from 35mm. transparencies employs one operator to load the transparencies into a storage magazine, from which they are fed into the machine automatically and after printing are unloaded by a second operator. Information relating to each transparency loaded into the magazine is punched on to standard 5-hole paper tape. Colour quality of the light is controlled by varying the phase relationship between synchronously rotating sectored filter discs, and the light output of an Xenon discharge lamp, both being operated from the same A.C. supply.     

Luminance Levels in Colour Transparencies and Reflexion Prints

The range of luminances perceivable in a projected transparency depends on the range of densities in the slide, the amount of flare in the projector and the amount of stray light on the screen. A survey has shown that a typical luminance range between whites and blacks in projected colour pictures is 2-1 log units. A similar survey for colour reflexion prints showed the range to be only 1-45 log units, because of the limited maximum density perceivable in typical viewing situations. The corresponding ranges of luminosities depend on the luminance levels and adaptation conditions involved. The implications of these facts for obtaining optimum quality in colour transparencies and reflexion prints are discussed.     

Surface Conduction Theory—A Functional Model Grain

Present-day subtractive colour photography is roughly classified into two systems; transmission-type colour films and reflection-type colour prints. The merits and demerits of them have been demonstrated by a computer simulation method from the viewpoint of colour reproduction quality, especially from the viewpoint of the gamuts and the excitation purities of reproducible colours, and the stability of selective neutral grey (illuminant metamerism).

It has been pointed out that the transmission-type colour films are superior to the reflection-type colour prints in the gamuts and the excitation purities of reproducible colours. On the other hand, the transmission-type colour films are inferior to the reflection-type colour prints in the stability of selective neutral grey.     

On Some Colour Properties of Dichroic Filters

The paper presents the study of colours due to the combination of two identical or two different dichroic filters put in natural light and of colours obtained with a single filter or the combination of two filters put in linearly polarized light if their mutual orientation or their orientation with respect to linearly polarized light is changed. It is shown that in the colour diagram the colours lie on straight lines and that generally they occupy a quadrangular region. On the basis of mathematical relations derived it was shown that the colours fulfil the additive law of colour mixing and that they may be approximately expressed by means of addition of four colours properly defined.     

Printing Colour Negatives

The problems encountered in making positive prints From negotives in colour photography are considered. An account is given of the various types of printer which have been devised in order to obtain a high yield of acceptable prints from negatives exposed by amateurs under widely varying conditions.     

用耐光档案墨喷墨打印耐久性强的单色照片

目前，企事业单位、宣传部门及广告行业印制出来的照片寿命往往不被人重视，尤其是那些有纪念意义、有艺术价值的名人作品应注重长久保存。本文提供了用耐光档案专用墨印制耐久性单色照片的方法，以供借鉴。     

The Preservation of Colour In Mounted Colour Prints

The main causes of dyes fading in photographic colour prints on paper or film are reviewed, and some suggestions to bear in mind while mounting colour prints, in order to reduce colour changes as far as possible, are described.     

Light Stability of New Polaroid Colour Prints

The new Polaroid ® instant colour print system, SX-70, uses metallized dyes, cyan, magenta, and yellow, which have superior light fastness properties. Structures for the dye developers are given, and also comparative fading data for the colour prints and a high quality commercial chromogenic colour print material. A further step of improvement has been achieved in another experimental colour print material using the same dyes. In the SX-70 print the processing chemicals remain with the picture.     

Accelerated wear testing for evaluating the life characteristics of copper–graphite tribological composite

Sliding wear is a key determinant of the performance of electrical sliding contacts used in electrical machines. The behavior of the contact in sliding couple is controlled by the mutual metal transfer, friction and wear. Product life and reliability of sliding contacts are dictated by wear phenomenon. The present paper focuses on evaluation of tribological performance of copper–graphite composites using reliability theory. These composites are made up of a high electrical and thermal conductivity matrix with a solid lubricant reinforcement, making it most suitable for sliding contacts. Traditional life tests under normal operating condition would be a time consuming process due to a very long expected life of the composite. Hence, accelerated wear testing was carried out for evaluating the life characteristics. Analysis was then performed on the times-to-failure data and reliability models were developed. Life-stress relationship based on the inverse power law-Weibull model was used to make reliability predictions at normal usage level.     

Appraisal of Land’s Work on Two-Primary Colour Projections

An analysis of the results of Land's experiments with two-primary colour projections has been carried out in terms of the known phenomena of object-colour perception. It is shown that no new theory is required for the prediction of Land’s result that two-primary colour projections can produce object-colour perceptions of all hues; nor for his result that many choices of pairs of primaries yield substantially the same object-colour perceptions. Land’s hypothesis that when the colours of the patches of light making up a scene are restricted to a one-dimensional variation of any sort, the observer usually perceives the objects in that scene as essentially without hue, is new; several special cases of it are supported by previous work as well as Land's. This hypothesis deserves the serious attention of research workers in object-colour perception.     

Dry sliding wear behavior of heat treated hybrid metal matrix composite using Taguchi techniques

Dry sliding wear behavior of zinc based alloy and composite reinforced with SiCp (9 wt%) and Gr (3 wt%) fabricated by stir casting method was investigated. Heat treatment (HT) and aging of the specimen were carried out, followed by water quenching. Wear behavior was evaluated using pin on disc apparatus. Taguchi technique was used to estimate the parameters affecting the wear significantly. The effect of HT was that it reduced the microcracks, residual stresses and improved the distribution of microconstituents. The influence of various parameters like applied load, sliding speed and sliding distance on wear behavior was investigated by means and analysis of variance (ANOVA). Further, correlation between the parameters was determined by multiple linear regression equation for each response. It was observed that the applied load significantly influenced the wear volume loss (WVL), followed by sliding speed implying that increase in either applied load or sliding speed increases the WVL. Whereas for composites, sliding distance showed a negative influence on wear indicating that increase in sliding distance reduces WVL due to the presence of reinforcements. The wear mechanism of the worn out specimen was analyzed using scanning electron microscopy. The analysis shows that the formation and retention of ceramic mixed mechanical layer (CMML) plays a major role in the dry sliding wear resistance.     

基于CycleGAN算法的凤翔木版年画色彩特征迁移研究

目的 为传承保护和创新发展陕西地区非物质文化遗产——凤翔木版年画,解决传统手工艺色彩复原难、图案组合创新效率低等问题,通过生成对抗网络与凤翔木版年画结合的方式,多维度推动其发展。方法 通过高清扫描、自适应阈值检测法、标准色值提取及数据增广等方式对其进行系统性归纳总结与标准化采集存储,建立凤翔木版年画数据集,利用CycleGAN算法训练网络模型以完成迁移实验。结果 通过艺术与技术的结合,不仅完成了年画墨线稿的色彩复原,还完成了创新设计图案的快速着色。结论 在凤翔木版年画的史料复原与设计应用方面,通过现代设计方法与色彩风格迁移功能的结合,使其在适应现代发展趋势、完成活态传承任务的同时,为同类研究提供新思路。     

Sun pictures: Printing Talbot's calotype negatives

Abstract

The inspiration for a major exhibition to commemorate the centenary of W. H. F. Talbot's death in 1877 arose from a number of projects in which the Kodak Museum had been involved. In September 1973, for the first programme in the BBC Television series ‘Pioneers of Photography’, the author visited Lacock Abbey to demonstrate Talbot's early photogenic drawing process. The sensitizing process used was based upon Talbot's own formulae, modified for use in a teaching programme prepared for the Kodak Education Service some years before¹. Thin paper, of the type used for making carbon copies of typewriting, of weight 45 grammes per square metre, was soaked in a solution of 50 grammes of sodium chloride in one litre of water until thoroughly wetted. The salted paper was dried, and sensitized when required by soaking in a solution of 100 grammes of silver nitrate in one litre of distilled water, to which 10 millilitres of glacial acetic acid had been added. About one minute was sufficient to convert the salt in the paper to silver chloride, and to give the necessary excess of silver nitrate to make a sensitive printing-out paper. When dried, the paper could be used to make prints by exposure to strong light under a leaf in a printing frame, yielding excellent prints in a few minutes in bright sunshine. Talbot stabilized his early pictures by treating them with a strong salt solution; to give greater permanence to the modern prints, they were fixed in conventional photographic fixing solutions. In the early summer of 1975, the same process was used to produce photogenic drawings both by contact and through the camera for display in the Fox Talbot Museum at Lacock, then under construction. During this work, some of Talbot's original calotype negatives were printed experimentally, while on loan from the Royal Photographic Society. Though not perfect, these modern calotype prints were sufficiently successful to suggest the possibility of an exhibition, to be prepared in honour of Talbot's centenary. It was intended that the display include a number of ‘salted paper’ prints from original negatives. It was felt that these would convey the special character of the calotype print far more effectively than would be possible with modern photographic materials.     

涂布纸水性油墨喷墨印品质量的影响因素研究

为了研究水性油墨喷墨印刷过程中喷印工艺参数对涂布铜版纸印品质量的影响,分析印品质量评价指标与喷印工艺参数间的正负相关性。印刷时,先改变喷墨印刷中喷头电压、点火频率、脉冲宽度的关键工艺参数,再测量印品实地密度、色差、明度和光泽度4个质量评价指标,定性分析各工艺参数对印品质量评价指标的正负相关性,最后采用统计学分析方法分析喷印工艺参数对印品质量的影响,并采用偏最小二乘回归法建立相应的回归模型。研究结果表明:脉冲宽度对涂布纸印品的实地密度、色差、光泽度、明度的影响较大,点火频率和喷头电压在一定范围内对涂布纸印品的实地密度、色差、光泽度、明度的影响较小,故在涂布纸水性油墨喷墨印刷过程中,通过合理地控制喷印工艺的关键参数可提高印品质量;偏最小二乘回归预测模型对印品的色差和明度具有较好的预测能力。     

柔印印品对化学品耐抗性的研究

采用黑、青、品三色水基柔印油墨在涂布纸上和非涂布纸上进行柔版印刷,通过L*a*b*值分析印品与水、油、乳酸、醋酸、盐酸、硫磺酸6种化学品的接触情况,最终确定最具耐抗性的印品及化学品,对于生产实践有一定指导意义。     

Phase noise in surface-acoustic-wave filters and resonators

Measurements of the phase noise modulation imparted on UHF carriers by surface-acoustic-wave (SAW) filters and resonators have been made using an HP 3047 spectrum analyzer. Three different types of SAW phase noise were observed. One type can be explained by temperature fluctuations. It is characterized by a spectral density of phase fluctuations which decreases as 1/f(2). The predominant noise mechanism in most SAW devices has a 1/f spectral density. The source of this noise is unknown, but it appears to be associated with both acoustic propagation and transduction. In filters fabricated on lithium niobate substrates, a third noise mechanism is evidenced. This mechanism produces nonstationary noise bursts that appear to originate in the transducer region. Experiments have been carried out on substrate materials, transducer metallizations, and over acoustic path lengths. The means by which low-frequency fluctuations are mixed to the carrier frequency have been studied.