Related Concept Videos
02:16Light Acquisition
In order to produce glucose, plants need to capture sufficient light energy. Many modern plants have evolved leaves specialized for light acquisition. Leaves can be only millimeters in width or tens of meters wide, depending on the environment. Due to competition for sunlight, evolution has driven the evolution of increasingly larger leaves and taller plants, to avoid shading by their neighbors with contaminant elaboration of root architecture and mechanisms to transport water and nutrients.
01:16Flame Photometry: Lab
In a flame photometer, when a solution like potassium chloride is aspirated into the flame, the solvent evaporates, leaving behind dehydrated salt. This salt dissociates into free gaseous atoms in their ground state. Some of these atoms absorb energy from the flame, leading to their excitation. The excited atoms return to the ground state, emitting photons at characteristic wavelengths. Because only electronic transitions are involved, the resulting emission lines are very narrow. The intensity...
01:02Flame Photometry: Overview
Flame photometry, also known as flame emission spectrometry, is a technique used for the qualitative and quantitative analysis of elements present in a sample using a flame as the source of excitation energy. The concept of flame photometry was realized in the early 1860s by Kirchhoff and Bunsen, who discovered that specific elements emit characteristic radiation when excited in flames. The first instrument developed for this purpose was used to measure sodium (Na) in plant ash using a Bunsen...
01:05Total Internal Reflection Fluorescence Microscopy
Total internal reflection fluorescence microscopy or TIRF is an advanced microscopic technique used to visualize fluorophores in samples close to a solid surface with a higher refractive index, such as a glass coverslip. TIRF only allows fluorophores in proximity to the solid surface to be excited. When light from a medium with a lower refractive index (such as air) hits the glass coverslip at a critical angle, the light undergoes total internal reflection stead of passing through the glass.
01:37Super-resolution Fluorescence Microscopy
Super-resolution fluorescence microscopy (SRFM) provides a better resolution than conventional fluorescence microscopy by reducing the point spread function (PSF). PSF is the light intensity distribution from a point that causes it to appear blurred. Due to PSF, each fluorescing point appears bigger than its actual size, and it is the PSF interference of nearby fluorophores that causes the blurred image. Various approaches to achieving higher resolution through SRFM have recently been developed.
02:26Photoelectric Effect
When light of a particular wavelength strikes a metal surface, electrons are emitted. This is called the photoelectric effect. The minimum frequency of light that can cause such emission of electrons is called the threshold frequency, which is specific to the metal. Light with a frequency lower than the threshold frequency, even if it is of high intensity, cannot initiate the emission of electrons. However, when the frequency is higher than the threshold value, the number of electrons ejected...
You might also read
Related Articles
Articles linked to this work by shared authors, journal, and citation graph.
Sort by
Same author
Integrating Agglomerative Perception with One-step Action Generation for Robotic Manipulation.
IEEE transactions on pattern analysis and machine intelligence·2026
Same author
Topology-Aware Segmentation Using Discrete Morse Theory.
... International Conference on Learning Representations·2026
Same author
TOPODIFFUSIONNET: A TOPOLOGY-AWARE DIFFUSION MODEL.
... International Conference on Learning Representations·2026
Related Experiment Video
Updated: Jun 20, 2026
11:57
Measuring Spatially- and Directionally-varying Light Scattering from Biological Material
Published on: May 20, 2013
Face relighting from a single image under arbitrary unknown lighting conditions.
Yang Wang1, Lei Zhang, Zicheng Liu
1Siemens Corporate Research, Princeton, NJ 08540, USA. wangy@cs.cmu.edu
IEEE Transactions on Pattern Analysis and Machine Intelligence
|September 19, 2009
Summary
This study introduces a novel 3D spherical harmonic basis morphable model (SHBMM) for face image manipulation under unknown lighting. The method enhances face recognition robustness, even in extreme lighting and with occlusions.
Area of Science:
- Computer Vision
- Computer Graphics
- Image Processing
Background:
- Modifying face image appearance under unknown illumination is challenging with single images.
- Spherical harmonics approximate Lambertian object appearances under varying light.
- Morphable models capture facial shape and texture variations.
Purpose of the Study:
- To develop a 3D spherical harmonic basis morphable model (SHBMM) for face appearance manipulation.
- To represent faces under arbitrary lighting and pose using low-dimensional SHBMM parameters.
- To improve robustness to extreme lighting and partial occlusions in face analysis.
Main Methods:
- Integrated spherical harmonics into a morphable model framework.
- Proposed a 3D SHBMM with shape, spherical harmonic basis, and illumination parameters.
- Developed a subregion-based framework using Markov random fields for texture modeling.
Main Results:
- The SHBMM effectively represents faces under unknown lighting and pose.
- The subregion-based approach enhances robustness to extreme lighting conditions.
- Demonstrated improved face recognition rates under challenging lighting scenarios.
Conclusions:
- The proposed SHBMM framework offers a robust method for face appearance manipulation.
- The integration of Markov random fields improves resilience to extreme lighting and occlusions.
- This approach advances face analysis techniques, particularly for recognition tasks.