#Colorconverter lab help software
In the 1990s, when computer hardware and software was mostly limited to storing and manipulating 8 bit/channel bitmaps, converting an RGB image to Lab and back was a lossy operation. In RGB or CMYK spaces, which model the output of physical devices rather than human visual perception, these transformations can only be done with the help of appropriate blend modes in the editing application.īecause Lab space is much larger than the gamut of computer displays, printers, or even human vision, a bitmap image represented as Lab requires more data per pixel to obtain the same precision as an RGB or CMYK bitmap. It can thus be used to make accurate color balance corrections by modifying output curves in the a and b components, or to adjust the lightness contrast using the L component. It aspires to perceptual uniformity, and its L component closely matches human perception of lightness. Unlike the RGB and CMYK color models, Lab color is designed to approximate human vision.
4.1 Approximate formulas for K a and K b.3.4 CIE XYZ to CIE L*a*b* (CIELAB) and CIELAB to CIE XYZ conversions.Also it is used as an interchange format between different devices as for its device independency.
in Adobe Photoshop when graphics for print have to be converted from RGB to CMYK, as the L*a*b* gamut includes both the RGB and CMYK gamut. This means that the colors are defined independent of their nature of creation or the device they are displayed on. One of the most important attributes of the L*a*b*-model is the device independency. The L*a*b* color space includes all perceivable colors which means that its gamut exceeds those of the RGB and CMYK color models. The lightness correlate in CIELAB is calculated using the cube root of the relative luminance. Often, in practice, the white point is assumed to follow a standard and is not explicitly stated (e.g., for "absolute colorimetric" rendering intent ICC L*a*b* values are relative to CIE standard illuminant D50, while they are relative to the unprinted substrate for other rendering intents). Lab values do not define absolute colors unless the white point is also specified. Both Lab spaces are relative to the white point of the XYZ data they were converted from. When storing colors in limited precision values, this can improve the reproduction of tones. Perceptually uniform means that a change of the same amount in a color value should produce a change of about the same visual importance. Strongly influenced by the Munsell color system, the intention of both "Lab" color spaces is to create a space which can be computed via simple formulas from the XYZ space, but is more perceptually uniform than XYZ. The color spaces are related in purpose, but differ in implementation.īoth spaces are derived from the "master" space CIE 1931 XYZ color space, which can predict which spectral power distributions will be perceived as the same color (see metamerism), but which is not particularly perceptually uniform. Thus the initials Lab by themselves are somewhat ambiguous. However, Lab is now more often used as an informal abbreviation for the CIE 1976 ( L*, a*, b*) color space (also called CIELAB, whose coordinates are actually L*, a*, and b*). The coordinates of the Hunter 1948 L, a, b color space are L, a, and b. Each axis of each square ranges from -128 to 128.Ī Lab color space is a color-opponent space with dimension L for lightness and a and b for the color-opponent dimensions, based on nonlinearly compressed CIE XYZ color space coordinates. Outline and description of enumerations, structures, and classes for creating and manipulating ICC Profiles as well as supporting conversions among the RGB, BGR, YUV, CMYK, HSV, HLS, YIQ, CMY, LAB, YCCK, Y41P, UYVY, YUY2, YVU9 and YCC color spaces.The CIE 1976 ( L*, a*, b*) color space (CIELAB), showing only colors that fit within the sRGB gamut (and can therefore be displayed on a typical computer display). LEADTOOLS will help you provide the correct color depth for whatever hardware your clients use, and enable you to create and manipulate ICC profiles for either software development or hardware manufacturing.įor an outline and description of enumerations, structures, classes, and delegates, click "Leadtools.ColorConversion" under Namespaces, below. LEADTOOLS can convert images from any color resolution to any other color resolution, from 1-bit to 64-bit, with multiple dithering methods using various palette options. LEADTOOLS Color Conversion functions provide many options to maximize image display quality for imaging purposes whether you are working with medical images, scanned documents or digital photographs.