Picasa Web Albums - Michael Jahn

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The multispectral scanner captures all relevant spectral light components of animage using this a several technologies, including ahigh-grade digital greyscale CCD camera in combination with 16 different opticalfilters and a stabilized D50 light source. The filters are put in front of thecamera successively, and an image is captured, respectively. From the 16 channels,the reflectance spectra of all pixels are reconstructed in 5nm steps within the visiblerange from 400 - 700 nm, taking the spectral properties of the camera, the filters, andthe lightsource into account. A white reference is used to correct for spatial non-uniformities.The data can be stored or encoded for data transmission and areindependent of the equipment and lightsource: spectral measurements can bederived from the multispectral images.

Normally, catalogers need to ship the garments to the photographer, then again to the prepress facility - this takes a great deal of time and incurs expense

When SID is used, you only need to ship the garments to the photographers, as the premedia re-toucher has a perfect image sample as a reference for color correction

Here is what the Photoshop Plugin looks like - on the left is the image captured using an RGB digital camera - on the left is the LAB image captured using SID - The basic idea here is to use the SID image to correct the image captured by the photographer.

Calibrated monitor (right hand side) Vewing area for originals or prints (left hand side) Three different standard light sources (typically D65 or D50, TL84 or CWF, A) Well defined viewing conditions Neutral grey surround Curtain for the elimination of ambient light

SID User Interface

SID Capture of the stuff that was in my briefcase

16 bit LAB image made from 16 channels of data made by SID - the next image is a RGB 8bit JPEG file exported (I did theis ONLY so it can be uploaded to this Picasa Web Album)

Created 3/26/08 10:02 AM by ColorAIXperts 2.1.0f2 Color AIXperts GmbH, Aachen, Germany Observer: CIE1931-2deg_5nm.CMF Illuminant: SI-D50_5nm.ill

This is a RHEM Indicator. The RHEM Light Indicator is printed with 2 magenta colorants which are a metameric pair. In this case when viewed under proper graphic arts lighting (5000K), these appear as a single smooth color; when viewed under non-standard lighting (e.g. incandescent or fluorescent), the color bands become visible again. This is used to visually verify your lighting conditions. When viewing proofs, prints and originals, lighting conditions can have a major impact on the appearance of colors. RHEM Indicator strips are a simple but effective tool which can show you if you are working in proper lighting conditions. If the RHEM Indicators show your standard lighting conditions are poor, a 5000K or D50 standardized lighting viewing booth may be a wise investment, as you simply cannot evaluate color without standardised lighting conditions

An example of a material that shifts color when different devices capture it.

The user application interface - an Adobe Photoshop plug-in

In the actual workflow, TIFF is used and the 8 bit RGB file has the Adobe RGB 1998 profile assigned to it for use in Adobe Photoshop - here, and operator is working on an image. Note that he does NOT need the actual fabric swatches in front of him to make the corrections !

of course, if the material was very metameric, the operator can quickly check both the SID image and the image that was captured by the photograher while in a D50 light booth (which is where his workstaion is with the calibrated EIZO monitor - using the X-Rite iOne and EIZO Color Navigator software

Here, note how the blue fabric was 'seen' by the camera as much too light as is the brown fabric, while the orange is okay - this is a metamerism issue.

Here, the two colors on the dress are corrected using the SID image capture. The AIX plug-in calculates the highlight, mid tone and shadow of the fabric and 'matches' them in the target image with the model.

Here is an example of a fabric that does not exhibit metamerisim very much - my simple digital camera, with the flash off did a fairly good job here, as the fabric and the screen seem to match pretty well.