Fast Tone Mapping for High Dynamic Range Images
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【浙江省自然科学基金】_自适应_期刊发文热词逐年推荐_20140811
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多峰函数 多参数拟合 在线建模 圆锥滚子轴承 图形处理器 图像融合 图像获取 图像绘制 图像处理 图像分析 图像分割 合作伙伴选择 发酵过程 反射 双向纹理函数 参数估计 参数优化 压缩 压力 区域生长 动态聚类 动态矩阵控制 动态模糊滑模控制 动平衡 动力学模型 功率分配 剩余能量 刚性转子 分簇算法 准入控制 入侵检测 光线空间插值 元对象协议 信道估计 优化设计 价格协作 人体行为识别 交流伺服系统 中子图像 不可见性 上行接入同步 α 稳定分布 zemike矩 x射线图像 truetime工具箱 s函数 petri网 levenberg-marquardt(l-m)算法 l-异亮氨酸发酵 ieee802.16e ieee 802.20 gpu boosting算法 apso
科研热词 遗传算法 正交频分复用 无线传感器网络 锐化增强 自适应遗传算法 自适应算法 自适应 滚动优化 模糊规则 拥塞控制 小波变换 优化调度 ad hoc网络 鲁棒性 预测控制 顶点着色器 非线性系统 隶属度函数 隔离小生境 随机延迟 随机优化 递阶优化 适应度函数 连续学习算法 运动历史图像 边缘跟踪 辐射度 软构件 路由协议 路径规划 超宽带 资源自适应分配 计量 蚁群算法 虚拟企业 色差分析 船舶协同设计 自适应解调 自适应细分 自适应滤波 自适应模糊控制器 自适应机制 自适应控制 自适应性 自适应微粒群算法 自适应局部学习 自适应变异 自由落体 网络控制系统 网格工作流 缺陷检测 细分曲面
LTE信令流程详解
L T E信令流程详解集团标准化工作小组 #Q8QGGQT-GX8G08Q8-GNQGJ8-MHHGN#LTE信令流程目录概述本文通过对重要概念的阐述，为信令流程的解析做铺垫，随后讲解LTE中重要信令流程，让大家熟悉各个物理过程是如何实现的，其次通过异常信令的解读让大家增强对异常信令流程的判断，再次对系统消息的解析，让大家了解系统消息的特点和携带的内容。
最后通过实测信令内容讲解，说明消息的重要信元字段。
第一章协议层与概念1.1控制面与用户面在无线通信系统中，负责传送和处理用户数据流工作的协议称为用户面；负责传送和处理系统协调信令的协议称为控制面。
用户面如同负责搬运的码头工人，控制面就相当于指挥员，当两个层面不分离时，自己既负责搬运又负责指挥，这种情况不利于大货物处理，因此分工独立后，办事效率可成倍提升，在LTE网络中，用户面和控制面已明确分离开。
1.2接口与协议接口是指不同网元之间的信息交互时的节点，每个接口含有不同的协议，同一接口的网元之间使用相互明白的语言进行信息交互，称为接口协议，接口协议的架构称为协议栈。
在LTE中有空中接口和地面接口，相应也有对应的协议和协议栈。
信令流数据流图1 子层、协议栈与流图2 子层运行方式LTE系统的数据处理过程被分解成不同的协议层。
简单分为三层结构：物理层、数据链路层L2和网络层。
图1阐述了LTE系统传输的总体协议架构以及用户面和控制面数据信息的路径和流向。
用户数据流和信令流以IP包的形式进行传送，在空中接口传送之前，IP包将通过多个协议层实体进行处理，到达eNodeB后，经过协议层逆向处理，再通过S1/X2接口分别流向不同的EPS实体，路径中各协议子层特点和功能如下：1.2.1NAS协议（非接入层协议）处理UE和MME之间信息的传输，传输的内容可以是用户信息或控制信息（如业务的建立、释放或者移动性管理信息）。
它与接入信息无关，只是通过接入层的信令交互，在UE和MME之间建立起了信令通路，从而便能进行非接入层信令流程了。
TONE CURVE MAPPING FOR HIGH DYNAMIC RANGE IMAGES
专利名称：TONE CURVE MAPPING FOR HIGH DYNAMIC RANGE IMAGES发明人：PYTLARZ, Jaclyn Anne,ATKINS, Robin 申请号：EP18706171.8申请日：20180212公开号：EP3559901B1公开日：20200805专利内容由知识产权出版社提供摘要：Methods for mapping an image from a first dynamic range to a second dynamic range are presented. The mapping is based on a function that includes two spline polynomials determined using three anchor points and three slopes. The first anchor N point is determined using the black point levels of the input and target output, the second anchor point is determined using the white point levels of the input and target output, and the third anchor point is determined using mid-tones information data for the input and target output. The mid-tones level of the target output is computed adaptively based on an ideal one-to-one mapping and by preserving input contrast in both the blacks and the highlights. An example tone-mapping transfer function based on third order (cubic) Hermite splines is presented.申请人：Dolby Laboratories Licensing Corporation代理机构：Dolby International AB Patent Group Europe更多信息请下载全文后查看。
HDR介绍
Dazzling ght （耀眼的光源）
Dazzling Reflection （耀眼的反射）
HDR Fresnel
在低反射率材质上 的明亮反射（Bright
reflection off low-reflectance surfaces）
Exposure Control（曝光控制）
具有真实感的景深效果（HDR Depth-of-Field）
1, What is HDR?
HDR = high dynamic range 一幅图像亮度级的最大值和最小值之比被称为动态范围 （Dynamic Range），定义如下： a = Imax / Imiin 真实世界场景中亮度的动态范围可达到 100,000 : 1 采用HDR，亮度值可以超过 [0..1] 的范围
Overview
What is HDR? What can be done with HDR? How to get HDR image? HDR File Format What does HDR require? HDR Rendering Process Typical HDR Workflow Tone Mapping HDR post-processing effects
7typicalhdrworkflowfakehdr8tonemappingmoreexactlytonemapping就是以某种方式将图像的动态范围进行缩放使之匹配只能输出ldr的现实设备的过程又称tonereproduction除了压缩亮度范围还必须保留原始图像的感观质量perceptualquality如原始图像对比度明亮程度细节等信息tonemapping的分类动态范围的重建算法大致分为两种空域不变spatiallyuniform或者叫全局范围动态压缩空域变化的spatiallyvarying或者叫局部动态范围压缩tonemapping之空域不变这类算法中以wardlarson等人avisibilitymatchingtonereproductionoperatorforhighdynamicrangescenes基于直方图调整的动态范围重建技术为标志优点此类算法在对图像进行动态范围变换时每个像素pixel上使用同一条变换曲线变换曲线可以预先指定或者根据图像的内容获取不足不变的变换曲线不能自适应图像的各个区域导致结果图像在细节颜色明亮程度上损失tonemapping之空域变化的该类算法针对图像不同的区域进行不同的变换根据人类视觉系统hvs的不同模型各种不同算法在压缩动态范围的同时都以保留图像质量的某一方面为标准直到90年代末期各种算法都是在多层模型上针对不同的hvs模型进行调整但是由于低频图像上采用的滤波函数hvs特性不佳在结果图像中物体边缘会产生严重光晕halo一直是困扰该类算法多年的问题1999年tumblin等人提出了lcis算法lcis
STA339BWS
with fast recall via I2C interface Bass/treble tones and de-emphasis control Selectable high-pass filter for DC blocking Advanced AM interference frequency
Digital gain/attenuation +48 dB to -80 dB with 0.5-dB/step resolution
Soft volume update with programmable ratio
Individual channel and master gain/attenuation
5
I2C bus specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.1 Communication protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.6 Power on/off sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4
Processing data paths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
technology Video apps: 576 x fS input mode supported Pin and SW compatible with STA333BW,
Digital gain/attenuation +48 dB to -80 dB with 0.5-dB/step resolution
Soft volume update with programmable ratio
Individual channel and master gain/attenuation
5
I2C bus specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.1 Communication protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.6 Power on/off sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4
Processing data paths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
technology Video apps: 576 x fS input mode supported Pin and SW compatible with STA333BW,
基于扩散张量的图像混合去噪方法
基于扩散张量的图像混合去噪方法
陈龙
【期刊名称】《价值工程》
【年(卷),期】2015(34)9
【摘要】图像去噪过程中,主要目的是有效去除噪声的同时能较好地保存图像的边缘与细节.基于此,本文根据自蛇模型与相干增强扩散的特征,提出了相应的混合去噪方法,并加入了保真项.实验结果表明该方法能有效去除图像噪声,同时对边缘信息的保留也较好.
【总页数】3页(P325-327)
【作者】陈龙
【作者单位】昆明理工大学理学院,昆明650500
【正文语种】中文
【中图分类】TP391.4
【相关文献】
1.基于方向扩散的线性扩散图像去噪方法 [J], 杜卫平
2.基于结构张量的前后向扩散图像去噪方法 [J], 杜婷;李浩;周绍光;苏博
3.一种新的混合震动滤波和各向异性扩散的图像增强和去噪方法研究 [J], 陈冠楠;杨坤涛;陈荣;谢志明;滕忠坚
4.非线性扩散图像混合滤波去噪方法研究 [J], 许韬
5.低剂量脑灌注CT图像恢复方法:基于先验图像约束扩散张量 [J], 牛善洲;刘宏;刘沛沄;张梦真;邱洋;黎钰;谢国强;刘国良;卢绍辉
因版权原因，仅展示原文概要，查看原文内容请购买。
NSG 2025 高端高速传输 爆发生成器商品说明书
NSG 2025The NSG 2025 is a high end burst generator and the choice for users who need the maximum in pulseamplitude/frequency capabilities, flexibility, coupling network features and EUT connectivity. Based on a 'building-block' concept, NSG 2025 lets you select and combine pulse generator, coupling and EUT adapters to create a flexible, upgradeable EMC test work station to match your needs today and into the future. It covers all the widely used burst test specifications of IEC, EN, ANSI-IEEE as well as the known extended manufacturer's requirements.Powerful Pulse GenerationThe NSG 2025 offers the most extensive range of pulse voltages and burst frequencies available in a single instrument. Pulses can be coupled into the mains supply voltage or applied as a pure high voltage for data and signal line testing.Pre-programmed IEC standard tests are available at the touch of a button and pulse parameters are user configurable -manually via front panel control or via PC-Windows software control. Not only does the NSG 2025 meet all the requirements of current world test standards with comfortable margins, it also anticipates likely future modifications with functions including a user-configurable burst frequency to 1MHz and extended selectable coupling modes.One System for all NeedsThe NSG 2025 'building block' design allows you to select the most appropriate modules for your application.Maximum voltage level, frequency range, current rating and coupling networks -single or three-phase - are selectable, with local or PC-based software control, or both.A wide range of test accessories isavailable for the NSG 2025 and, forcomplete integrated EMC test andmeasurement, the NSG 2025 is fullycompatible with the Schaffner ProfLinesystem. Testing products for world-widemarkets is easy with the NSG 2025.The supply voltage is switchable between110/115V and 220/240V, and country-specific power-line sockets for the EUTare interchangeable so full complianceand volume production tests can be runon finished products andsystems destined for different markets.Built-in SafetyEvery component in the NSG 2025 thatcarries a high voltage is designed to beinherently safe, with interlock featuresbuilt into the hardware, ensuringautomatic power-down in case ofviolation of any safety condition.Manual ControlThe standard, pre-programmed IEC testscan be called up, and used straight awayor be modified and saved. All testparameters including pulse amplitude,duration, rise time and polarity as well asburst frequency, duration and phase anglecan be set manually, for custom testing.Up to eight different custom tests can besaved and used again or modified atany time.Software ControlThe WIN 2025 Windows-based softwaremodule allows remote, real-time accessto all the instrument functions andprovides a whole range of additional testsequencing, programming and reportingcapabilities. With a just few simple point-and-click operations, engineers can settest parameters directly, or can set upand save tests, drastically reducing set-up times for repeated tests and avoidingpotential errors in re-keying information.Any of the saved, pre-programmed orcustom tests can easily be combinedinto a sequence for automatic execution.When the sequence is run, WIN 2025executes each of the tests in turn,without any need for further operatorintervention. This allows engineers tooptimise test procedures and to managelaboratory test time efficiently formaximum throughput.Professional ReportingA sophisticated report generator providesautomatic reporting of results in aprofessional format - with a facility foron-line addition of engineers' comments.These records provide an invaluablereference for design engineers throughoutthe verification process and meet legalrequirements for proof of compliancetesting.NSG 2025 - Available ModelsOptions WIN 2025 Software control packageCDN 8015 Capacitive coupling clamp according to IEC 61000-4-4 with SHV connector and interlock, including interconnection cables INA 161Rack mounting brackets.Adapters for EUT connection with national plugs INA 250 IEC 309 32A 3-phase (red) for max burst voltage 8kV INA 251 IEC 309 16A 1-phase (blue) for max burst voltage 8kV INA 252 Germany, Schuko 1-phase 16A INA 253 Switzerland, 1-phase 10A INA 254 France, 1-phase 16A INA 255 GB, 1-phase 13A INA 256 US, 1-phase 15AINA 260 Warning lamp assemblyINA 261 Separate SHV plug for 5mm cables INA 262 Universal safety plug setINA 303A Optical link set (230V), 10m opto cable INA 304A Optical link set (115V), 10m opto cable INA 305AOptical link set (100V), 10m opto cable。
tidu
devices, while preserving as much of their visual content as possible? This is precisely the problem addressed in this paper.
The problem that we are faced with is vividly illustrated by the series of images in Figure 1. These photographs were taken using a digital camera with exposure times ranging from 1/1000 to 1/4 of a second (at f/8) from inside a lobby of a building facing glass doors leading into a sunlit inner courtyard. Note that each exposure reveals some features that are not visible in the other photographs1. For example, the true color of the areas directly illuminated by the sun can be reliably assessed only in the least exposed image, since these areas become over-exposed in the remainder of the sequence. The color and texture of the stone tiles just outside the door are best captured in the middle image, while the green color and the texture of the ficus plant leaves becomes visible only in the very last image in the sequence. All of these features, however, are simultaneously clearly visible to a human observer standing in the same location, because of adaptation that takes place as our eyes scan the scene [Pattanaik et al. 1998]. Using Debevec and Malik’s method [1997], we can compile these 8-bit images into a single HDR radiance map with dynamic range of about 25,000:1. However, it is not at all clear how to display such an image on a CRT monitor whose dynamic range is typically below 100:1!
磁共振成像技术中英文名词对照
反转恢复快速自旋回波
Inversion recovery turbo spin echo , IR-TSE
反转恢复快速自旋回波
Liver acquisition with volrme acceleration ,LAVA
肝脏容积加速采集
Line scan , LS
线扫描
Magnetization prepared fast gradient recalled echo,MP-FGRE
特殊吸收比率
Fregnal acquisition
信号采集
signal sampling
信号采样
data acquisition
数据采集
raw data
原始数据
Analogue to digital converter , ADC
模数转换器
磁共振成像技术中英文名词对照
abdomen
腹部
Apparent diffusion coefficient, ADC
表现扩散系数
Analog-digital conversion ,ADC
模数转换
Arterial spin labeling ,ASL
动脉自旋标记
Balance fast field echo ,B-FFE
平衡式快速场回波
Blood oxygenation level dependent ,BOLD
血氧水平依赖
Balance steady state free preceesion ,Balance-SSFP
平衡式稳态自由进动
Continuous arterial spin labeling ,CASL
回波间隙
Echo trainlength ，ETL
Inversion recovery turbo spin echo , IR-TSE
反转恢复快速自旋回波
Liver acquisition with volrme acceleration ,LAVA
肝脏容积加速采集
Line scan , LS
线扫描
Magnetization prepared fast gradient recalled echo,MP-FGRE
特殊吸收比率
Fregnal acquisition
信号采集
signal sampling
信号采样
data acquisition
数据采集
raw data
原始数据
Analogue to digital converter , ADC
模数转换器
磁共振成像技术中英文名词对照
abdomen
腹部
Apparent diffusion coefficient, ADC
表现扩散系数
Analog-digital conversion ,ADC
模数转换
Arterial spin labeling ,ASL
动脉自旋标记
Balance fast field echo ,B-FFE
平衡式快速场回波
Blood oxygenation level dependent ,BOLD
血氧水平依赖
Balance steady state free preceesion ,Balance-SSFP
平衡式稳态自由进动
Continuous arterial spin labeling ,CASL
回波间隙
Echo trainlength ，ETL
【国家自然科学基金】_动态成像_基金支持热词逐年推荐_【万方软件创新助手】_20140802
自动增益控制 脾胃湿热证 脑血管意外 脑缺血发作 脑缺血 脉搏波形 脉搏图像传感器 胞浆游离ca2+浓度 肿瘤 肺动脉平滑肌细胞 肝脏 肝癌 肝 结构光 细胞种类 细胞存活 细胞增殖 细胞培养 细胞分裂周期42蛋白 细胞分化 细胞内分布 组织病理 纳秒级时间选通 约束条件 红外目标跟踪 红外图像产生 红外图像 立体匹配 空间相机 移植动物模型 神经递质 神经精神疾病 神经元可塑性 磁共振磁共振成像 磁共振波谱学 磁共振成像,弥散 矿震 短暂性 眼睛波前畸变 相关分析 相位 相似度量 监护 皮肤 病例对照研究 电阻率 电阻抗成像 电磁波 电导率 电子自旋共振成像 生物电阻抗 玻璃芯片 狗 特征参数
焦斑 火线检测 火烧迹地 激光散斑 激光干涉法 激光共聚焦显微镜 溶质运移 湿法刻蚀 淋巴瘤,颅内 液晶空间光调制器 海马 波谱 油井 污染过程 氯胺酮 氮氧自由基 气道上皮 气态甲醛 毫米波辐射计 模型 检测前跟踪 梗阻性肾积水 核密度估计 核函数 显微成像 明确识别 时间序列 无源毫米波成像 数据采集系统 数字微镜阵列 数字减影 散斑照明 控制矩阵 探针 探测技术 探地雷达 损伤修复 振幅 手语 成像质量 成像测量 成像技术 成像 情绪 急性脑缺血 快速图像拼接 心肌细胞 心室功能,左 微震监测 弥散加权成像 应变成像 序贯相似性检测算法 并行算法 左心室
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Fast Tone Mapping for High Dynamic Range Images
Jiang Duan and Guoping Qiu School of Computer Science, The University of Nottingham {jxd | qiu} @ sequence of low dynamic range (LDR) images of the same scene taken under different exposure intervals.
Abstract
We present a fast, effective and flexible tone reproduction method that preserves visibility and contrast impression of high dynamic range scenes in low dynamic range reproduction devices. A single parameter controls the visibility and contrast in a simple and elegant manner and at interactive speed. The new method is simple to use and is computationally highly efficient. Experiments show that the technique produces good results on a variety of high dynamic range images. The method can also be used to enhance ordinary low dynamic range digital images.
2. Related Work
There has been increasing interest in high dynamic range image. In the past decade or so, a number of techniques
have been developed for tone reproduction for high contrast images. There are two broad categories of technology, i.e., tone reproduction curve (TRC) based and tone reproduction operator (TRO) based [2]. TRC refers to techniques that manipulate the pixel distributions. Earlier pioneering work in this category include that of [3] which introduced a tone reproduction method that attempted to match display brightness with real world sensations. More recently, [4] presented a tone mapping method that modeled some aspects of human visual system. Perhaps the most comprehensive technique in this category is that of [5], which introduced a quite sophisticated tone reproduction curve technique that incorporated models of human contrast sensitivity, glare, spatial acuity and color sensitivity. TRO techniques involve the spatial manipulation of local neighboring pixel values, often at multiple scales. The scientific principle of this type of technique is based on the image formation model: I(x, y) = L(x, y) R(x, y), which states that image intensity function I(x, y) is the product of the luminance function L(x, y) and the scene reflectance function R(x, y). Because real world reflectance R(x, y) has low dynamic range (normally not exceeding 100:1), reducing the dynamic range of I(x, y) can be achieved by reducing the dynamic range of L(x, y) if one could separate L(x, y) from R(x, y). Methods based on this principle include [6], [7] and [8]. They mainly differ in the way in which they attempted to separate the luminance component from the reflectance component. Recent development has also attempted to incorporate traditional photographic technology to the digital domain for the reproduction of high dynamic range images [9]. A very impressive latest development in high dynamic range compression is that of [10]. Based on the observation that human visual system is only sensitive to relative local contrast, the authors developed a multiresolution gradient domain technique. TRC methods do not involve spatial processing, they are therefore computationally very fast. TRO methods involve multiresolution spatial processing and are therefore computationally more expensive. Because TRO methods can reverse local contrast, they can sometimes cause “halo” effects in the reproduction. Another difficulty of traditional techniques is that there were too many parameters the users have to set which made them quite difficult to use.
Figure 1, Digital photos of the same scene taken with different exIntroduction
The real world scenes we experience in our daily life often have a very wide range of luminance values. Human visual system is capable of perceiving scenes over five orders of magnitude and can gradually adapt to scenes with dynamic ranges of over nine orders of magnitude. With the rapid advancement of digital imaging technology, there is increasing interest in taking digital photographs that capture the full dynamic range of the scene of view. Although it is conceivable that future digital cameras would be able to capture high dynamic range (HDR) photos by the click of a button, current technology often only enables part of the real world high dynamic scene visible in any one single shot. Figure 1 illustrates such a scenario. This is an indoor scene with the sunlight shining through the window and the camera was placed at the dark end. In order to make the features near the window visible, shorter exposure was used. However, this made the scene further away from the light source too dark. To make the features in the dark end visible, we increased the exposure interval. This time, on the other hand, the areas near the window became saturated. To human observers, however, all features in the darkest as well as the brightest areas are equally clearly visible simultaneously. How to make all these features with such a wide range of radiance simultaneously visible in a single digital photo is the problem we are addressing in this paper. In fact, recent technologies have made it relatively easy to create numerical luminance maps that capture the full dynamic range of real world scene [1]. A HDR radiance map of a scene can be generated by using a
Jiang Duan and Guoping Qiu School of Computer Science, The University of Nottingham {jxd | qiu} @ sequence of low dynamic range (LDR) images of the same scene taken under different exposure intervals.
Abstract
We present a fast, effective and flexible tone reproduction method that preserves visibility and contrast impression of high dynamic range scenes in low dynamic range reproduction devices. A single parameter controls the visibility and contrast in a simple and elegant manner and at interactive speed. The new method is simple to use and is computationally highly efficient. Experiments show that the technique produces good results on a variety of high dynamic range images. The method can also be used to enhance ordinary low dynamic range digital images.
2. Related Work
There has been increasing interest in high dynamic range image. In the past decade or so, a number of techniques
have been developed for tone reproduction for high contrast images. There are two broad categories of technology, i.e., tone reproduction curve (TRC) based and tone reproduction operator (TRO) based [2]. TRC refers to techniques that manipulate the pixel distributions. Earlier pioneering work in this category include that of [3] which introduced a tone reproduction method that attempted to match display brightness with real world sensations. More recently, [4] presented a tone mapping method that modeled some aspects of human visual system. Perhaps the most comprehensive technique in this category is that of [5], which introduced a quite sophisticated tone reproduction curve technique that incorporated models of human contrast sensitivity, glare, spatial acuity and color sensitivity. TRO techniques involve the spatial manipulation of local neighboring pixel values, often at multiple scales. The scientific principle of this type of technique is based on the image formation model: I(x, y) = L(x, y) R(x, y), which states that image intensity function I(x, y) is the product of the luminance function L(x, y) and the scene reflectance function R(x, y). Because real world reflectance R(x, y) has low dynamic range (normally not exceeding 100:1), reducing the dynamic range of I(x, y) can be achieved by reducing the dynamic range of L(x, y) if one could separate L(x, y) from R(x, y). Methods based on this principle include [6], [7] and [8]. They mainly differ in the way in which they attempted to separate the luminance component from the reflectance component. Recent development has also attempted to incorporate traditional photographic technology to the digital domain for the reproduction of high dynamic range images [9]. A very impressive latest development in high dynamic range compression is that of [10]. Based on the observation that human visual system is only sensitive to relative local contrast, the authors developed a multiresolution gradient domain technique. TRC methods do not involve spatial processing, they are therefore computationally very fast. TRO methods involve multiresolution spatial processing and are therefore computationally more expensive. Because TRO methods can reverse local contrast, they can sometimes cause “halo” effects in the reproduction. Another difficulty of traditional techniques is that there were too many parameters the users have to set which made them quite difficult to use.
Figure 1, Digital photos of the same scene taken with different exIntroduction
The real world scenes we experience in our daily life often have a very wide range of luminance values. Human visual system is capable of perceiving scenes over five orders of magnitude and can gradually adapt to scenes with dynamic ranges of over nine orders of magnitude. With the rapid advancement of digital imaging technology, there is increasing interest in taking digital photographs that capture the full dynamic range of the scene of view. Although it is conceivable that future digital cameras would be able to capture high dynamic range (HDR) photos by the click of a button, current technology often only enables part of the real world high dynamic scene visible in any one single shot. Figure 1 illustrates such a scenario. This is an indoor scene with the sunlight shining through the window and the camera was placed at the dark end. In order to make the features near the window visible, shorter exposure was used. However, this made the scene further away from the light source too dark. To make the features in the dark end visible, we increased the exposure interval. This time, on the other hand, the areas near the window became saturated. To human observers, however, all features in the darkest as well as the brightest areas are equally clearly visible simultaneously. How to make all these features with such a wide range of radiance simultaneously visible in a single digital photo is the problem we are addressing in this paper. In fact, recent technologies have made it relatively easy to create numerical luminance maps that capture the full dynamic range of real world scene [1]. A HDR radiance map of a scene can be generated by using a