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Topic: Lab color space

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In the News (Sat 20 Apr 19)

  Lab color space - Wikipedia, the free encyclopedia
The Hunter Lab Color Space as an Adams Chromatic Valance Space
Therefore, the Hunter Lab color space is an Adams Chromatic Valance space.
CIE 1976 L*a*b* is based directly on the CIE 1931 XYZ color space as an attempt to linearize the perceptibility of color differences, using the color difference metric described by the MacAdam ellipse.
en.wikipedia.org /wiki/Lab_color_space   (1159 words)

 What is Color space   (Site not responding. Last check: 2007-10-09)
Since "color space" is a more specific term for a certain combination of a color model plus a color mapping function, the term "color space" tends to be used to also identify color models, since identifying a color space automatically identifies the associated color model.
These spaces, such as Pantone, are in effect a given set of names or numbers which are defined by the existence of a corresponding set of physical color swatches.
It corresponds closely to the YUV scheme used in PAL television except that the YIQ color space is rotated 33° with respect to the YUV color space.
www.whatis.tv /Color_space.html   (850 words)

 Space Lab -- Recommendations and Resources   (Site not responding. Last check: 2007-10-09)
The three parameters in the model represent the luminance of the color (L, the smallest L yields fl), its position between red and green (a, the smallest a yields green) and its position between yellow and blue (b, the smallest b yields blue).
LAB is an acronym for the League of American Bicyclists, a bicyclist advocacy organization.
Lab is used to refer to the Lab color space; ''Lab'' is simplified from the formal name ''L*a*b*''.
www.becomingapediatrician.com /health/135/space-lab.html   (988 words)

 Determining the best Color Space for compression   (Site not responding. Last check: 2007-10-09)
Now that we know in each color space which are the components that we can subsample without increasing too dramatically the distortion we need to compare the four color spaces.
Indeed for example the colors of peppers are green and red : one of the opponent colors channel.
For example in a color space in which the interchannel cross correlation is high, information will be coded redundantly and and this will lead to lower compression ratios.
www.stanford.edu /~esetton/experiments2.htm   (568 words)

 Sharpening -- Part IV
RGB color spaces have three channels, one for each of the three colors (i.e., red, green, and blue).
Rather than three color channels, the LAB color space has a lightness channel, that stores the tonal information, and two color channels, channel "a" that stores the blue/yellow information and channel "b" that stores the green/red information.
In LAB sharpening, the image is converted to the LAB space and the sharpening is conducted on the lightness channel only.
ronbigelow.com /articles/sharpen4/sharpen4.htm   (2632 words)

 Design Features: Desktop Color, Part One
I use an ICC profile that describes the color gamut of the scanner (while scanning a particular film), to transform the scanned image from the scanner’s gamut into the color gamut of the rgb or lab color space I will use for my master digital file.
The lab color space is the color gamut of the human eye, so if you create your master image in lab color, you won’t be throwing out any colors that the human eye can see.
Working in lab color is a little different than working in an rgb color, but it does give you this advantage of matching the eye’s color space.
www.commarts.com /CA/feadesign_d/color4x/02_colorx.html   (784 words)

Lab color model, on the other hand, can describe more colors than RGB space, so re-processing your luminosity and color data using that methods improves the final appearence of the color composite image.
While color information in filtered images was most probably already uneven (due to lower signal-to-noise ratio), its distribution was further affected by data reduction into HSL color space.
Then, it can be used in Lab color space as a new L layer with "a" and "b" data derived from the original RGB image (after conversion to Lab space as well).
www.astrosurf.com /jwisn/improving.htm   (1327 words)

 AIM: What is Wrong with the CIE Lab Specification
The problem with the CIE Lab is that it is nowhere near perceptually uniform color space.
L1, a1 and b1 are the Lab values of color 1 and L2, a2 and b2 are the Lab values of color 2.
The evaluations are overlaid on a quite typical photograph, this is because the aim of this evaluation is to assess the usefulness of the Lab color-space and the dE* as a color-difference measure for photographic imaging purposes.
www.aim-dtp.net /aim/evaluation/cie_lab   (1030 words)

 CGSD Gamma Correction and Color Space   (Site not responding. Last check: 2007-10-09)
Gamma does not affect the representation of a color in all color spaces equally and has no affect on color representation in many color spaces.
An image in Lab space (Photoshop calls this Lab Mode) should not be affected by gamma.
The colors were made in Adobe Photoshop in Lab color space and converted to RGB space using the gamma mentioned.
www.cgsd.com /papers/gamma_colorspace.html   (354 words)

 Photoshop Training with Dan Margulis
You also have to get into LAB from something (RGB usually) and while Photoshop does this with 20 bit precision, every time you convert from a smaller to a wider gamut space in 8 bit, especially with a color space gamut mismatch, you lose even more data.
If one uses 8 bit colors and generates sufficient adjacent color differential as the direct result of an edit, then there may be a case for the use of 16 bit color.
The eye blends colors quite well and uses a built in AWB to compensate for what we “think” the right color is or should be.
www.ledet.com /margulis/ACT_postings/ColorCorrection/ACT-16bit-LAB.htm   (9747 words)

 creativepro.com - Inside Photoshop: The Color Lab
Unlike RGB colors that are screen-dependent and CMYK colors that vary with printer, ink and paper characteristics, CIE Lab colors are device-independent.
In Photoshop, the Lab mode consists of three color channels, as shown in Figure A. The first channel is Lightness (L).
Lab colors are convenient and fun to work with.
www.creativepro.com /story/feature/12869.html   (1316 words)

 What is CIE 1976 (L* a* b*) colour space?   (Site not responding. Last check: 2007-10-09)
There are perhaps two problems with the specification of colours in terms of tristimulus values and chromaticity space.
The need for a uniform colour space led to a number of non-linear transformations of the CIE 1931 XYZ space and finally resulted in the specification of one of these transformations as the CIE 1976 (L* a* b*) colour space.
In fact in 1976 the CIE specified two colour spaces; one of these was intended for use with self-luminous colours and the other was intended for use with surface colours.
www.colourware.co.uk /cpfaq/q3-21.htm   (312 words)

 MacDermid ColorSpan Inc. - High resolution large format and wide format inkjet color printers.
Lab is a theoretical color model that describes color in three planes: L, a, and b.
This color model is not tied to any display/output device, as is the case with RGB and CMYK.
This color model is consequently considered a 'device-independent' color model, and does not carry with it the inherent gamut limitations of monitors or printers.
www.colorspan.com /support/tutorials/cmpl/lab.asp   (169 words)

 Color Spaces, Device Characterization, and Color Management in Photoshop 7 > What Is Color & How We See It   (Site not responding. Last check: 2007-10-09)
The inks or other types of color that are painted on that paper will subtract further wavelengths from that original light and reflect back different colors that are the remaining nonsubtracted wavelengths.
Color on a computer monitor comes from particle energizers, a type of light source, behind the monitor's glass that hits the coating on the inside of the monitor glass and produces different colors and light intensities depending on the numerical values that are driving the different colored light particle energizers.
When you see color by looking at a slide on a light table, the color you see there depends on the color of the light source behind the slide, the colors in the emulsion of the slide material, and also on the amount and intensity of the other light sources in the room.
www.informit.com /articles/article.asp?p=30296&seqNum=2   (719 words)

 Understanding color space and gamut
A color space is a range of colors in the visible spectrum.
Some colors within the gamut of your computer monitor are not within the gamut of your inkjet printer, and vice versa.
When a color cannot be produced on a device, it's considered to be outside the color space of that particular device.
www.pdesigner.net /photoshopcs/1_6_3_1.html   (193 words)

 Post-processing outdoor digital color photographs   (Site not responding. Last check: 2007-10-09)
Whenever possible, convert to Lab color mode and sharpen only the luminance or lightness channel after resampling to final image size and resolution.
For color images, a very useful variation on Paul's approach takes advantage of the clean separation of luminance (brightness) and chrominance (color) data available in the Lab color space, a powerful alternative to the more familiar RGB color space.
Michael Cervantes' practical PHOTO-PAINT Lab color tutorial, The Magic of Lab Color Space, is a great introduction to the miracles one can work with Lab-based photo editing.
dpfwiw.com /processing.htm   (2050 words)

 RetouchPRO - LAB color space
As a everyday standard working space or editing space to perform the majority of your colour work in - LAB is perhaps not the best choice, which is why larger gamut idealised RGB working spaces exist.
LAB is a superior space for sharpening, for many color operations that simply aren't possible in RGB or CMYK and for any retouching that involves blending different colors into each other, and for most types of cast removal.
L*A*B is not a must part of the technique.
www.retouchpro.com /forums/showthread.php?t=4057   (1005 words)

 ImagePro>Re: Hunter LAB Color Space
Hi Mark, Starting from version 4.5 IPP can be calibrated and measure XYZ and CIE Lab color coordinates.
We've just released Color-Pro plugin module for IPP (http://www.mediacy.com/colorpro/colorpro.htm) that enables color management using color profiles (ICC,ICM) providing correct presentation of acquired images on monitors and printers and measurements of XYZ and CIE Lab coordinates based on color profiles.
Essentially I found > the > Macbeth color chart, which obviously is very useful for calibrating RGB to > XYZ, LAB values in terms of color.
www.mediacy.com /tech/ipuml/2004/msg00386.html   (551 words)

 Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace   (Site not responding. Last check: 2007-10-09)
At the end of the day the book describes working with a less used color space, describes the characteristics of the space and then describes what are the situations that are best addressed in this space and also the situations that should not be tackled here (even though conventional wisdom prescribes otherwise).
However, if you work with digital images in Photoshop or other similar software that support the LAB color space, then I believe this book is indispensible for increasing your understanding of how to make superior color corrections that are not otherwise possible using RGB alone.
But for those images for which it is appropriate, it will provide fast color correction with results that can be superior to using RGB and in many cases that would otherwise not be possible to achieve.
www.24hourtalk.com /books/isbn0321356780.html   (1405 words)

 ACHUKASTORE - Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace - Book
Nowhere is that magic more apparent than in its LAB color processing capabilities, which can make even the subtle canyon colors of rock, sand, and dirt come to vivid life.
Developed in 1976, the LAB color space is a means to expedite color conversions to an industry standard.
If you have images which are flat, need color correcting, need a color shift, noise removal, better sharpening, blending............I could go on and on, then this is the book for you.
www.achuka.co.uk /amstore/info.php?asin=0321356780   (1559 words)

 Noise and sharpening > Add noise with the Add Noise filter   (Site not responding. Last check: 2007-10-09)
This means that any color is just as likely as another to be used to produce the effect.
Since colors are set to a specific range, the colors of Gaussian noise more closely resemble the colors of your image.
This option is a good idea when you're working on images with areas of solid color, but a bad choice if you're trying to blend contrasting areas of color together.
www.peachpit.com /articles/article.asp?p=412363&seqNum=6   (876 words)

 Adobe Open Source: LAB Color Space
Constructs and utilities specific to the LAB color space.
Represents a pointer to a planar LAB pixel.
A pointer can be constructed from and assigned to the address of a value, the address of a reference or another pointer It can also be dereferenced returning a reference.
opensource.adobe.com /group__LAB.html   (63 words)

 ImagePro>Hunter LAB Color Space
Essentially I found the Macbeth color chart, which obviously is very useful for calibrating RGB to XYZ, LAB values in terms of color.
I have found on the archive list: RE: ImagePro> Color Calibration From: Yuri Gaidoukevitch (yuri@mediacy.com) Date: 07/30/99 This is most useful but I could do with some further information/assistance on Hunter LAB specifically.
So if anyone has done work with this color space and or has Hunter LAB color charts I'd be most grateful.
www.mediacy.com /tech/ipuml/2004/msg00385.html   (256 words)

 SVDV-Photography - LAB Color Boost (Video Tutorial)   (Site not responding. Last check: 2007-10-09)
The LAB color-space has many advantages over other more traditional color-spaces.
First and foremost, Lab-based editing allows brightness and color data to be manipulated in isolation.
Sharpening and other spatially-oriented post-processing operations are also best performed on the L channel in Lab color mode.
svdv-photography.net /nuc/index.php?itemid=15   (216 words)

 Re: [Lcms-user] Using Lindbloom's UP Lab color space
I would like to convert images with embedded profiles into this space, do some manipulations, and then back again to write the output files.
Hi, I have a question about using Bruce Lindbloom's UP Lab color space with lcms.
I expect there is a good reason why Lindbloom's profile has UP Lab where the PCS usually goes and regular Lab where the output usually goes.
www.mail-archive.com /lcms-user@lists.sourceforge.net/msg01263.html   (548 words)

 SF Bay Area Photography :: View topic - soocool tech tips #1: Recovering OVERBLOWN highlights
This isn't a problem in the LAB color space.
LAB and repainting yellow on the BRIGHTEST part of the sun in
Step 2: Set a proper small brush size and paint into the overblown highligh area with a similar color from near the blown highlights.
www.soocool.com /forum/viewtopic.php?t=1820   (888 words)

 Digital Darkroom Forum: Web-based LAB color space tutorials
I understand this is a great space to adjust colors, but I am looking for some insightful, free help.
He recently wrote a book called Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace.
I rarely use Lab myself, but I ran across this interesting thread on another forum some time ago.
www.photo.net /bboard/q-and-a-fetch-msg?msg_id=00GLK1   (276 words)

 Amazon.com: Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace: Books: Dan ...   (Site not responding. Last check: 2007-10-09)
"Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace" by Dan Margulis is definitely worth reading and is most entertaining.
To me the biggest discovery was the idea of using curves in LAB color space to increase color variability.
His explanation for why we want this is that cameras lack the sense of simultaneous contrast common to most human beings.
www.amazon.com /exec/obidos/tg/detail/-/0321356780?v=glance   (2460 words)

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