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HCT User Guide

page 8

Copyright © 2001 HutchColor, LLC

User_Guide_43.docx 2/10/19

Scanner profiling

Scanning or capturing the target

Make sure the target is clean and mounted in the same manner as live work. Scan the target without
USM and save it as an RGB TIFF image, with at least 750 pixels in the long dimension, or as
required by your software. Larger files will not increase profile quality. 16-bit-per-channel files may
improve profile quality (slightly), especially if the device’s default response is very dark or light. For
setup tips see the ‘Scanning_Guide’ at

www.hutchcolor.com/CMS_notes.html

. Pay particular

attention to disabling automatic features, fixed end points and optimized tone curve.

Qualifying the target scan

Ideally, every patch in the target scan must contain slightly different values from it’s neighbor
patches. No patch should have RGB values as high as 255 or as low as 0. Failure to observe these
rules may lead to clipping or reversals in the profile.

CCD scanner evenness

Flatbed scanners, especially some 35mm slide scanners, often suffer from uneven illumination
across the image which will negatively affect profile accuracy. To check for evenness, scan a flat tint
of evenly-exposed slide film (about 0.30 to 0.60 density) and examine the RGB values across the
entire area. Variations greater than +/- 002 in either R, G or B across the frame (ignoring dust or
scratches) may be cause for alarm.

Scanner flare

Most flat bed scanners - especially 35mm scanners - suffer from enough optical flare to reduce
profile quality. This happens when light is scattered from neighboring patches or clear areas
surrounding the target. Profile errors due to flare include excessive contrast, plugged shadow tones,
incorrect gray balance and inaccurate colors.
Flare can be detected by opening a typical scan and temporarily setting a high gamma number, like
3.0, in Photoshop. (Gamma is the middle slider in the Levels control.)

Flare in a typical 35mm scanner, with normal gamma (left) and gamma 3.0 (right)

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Содержание HCT

Страница 1: ...USER GUIDE Version 43 February 2019 ...

Страница 2: ...ow detail 11 Extending highlight detail 13 Lightening dark 35mm profiles 13 Auto lightening profiles 14 Pseudo chrome profiles 15 The Kodachrome difference 15 Requirements 15 Preparation 15 Correcting gray balance 16 Correcting individual color hues 17 Modifying the HCT scan 17 Saving the modified HCT scan 19 Making the pseudo chrome profile 19 Testing the new profile 20 Camera profiling 21 Defini...

Страница 3: ...HCT 31 Water based cleaning extreme cases only 31 Longevity 32 Testing the target 32 Frequently asked questions 33 Older reference file date 33 Does my software support the HCT 33 Grainy or noisy scans 33 MonacoPROFILER rejects the target scan 33 Gray patches not neutral 34 Dark 35mm profiles 34 HCT profiles darker than IT8 profiles 35 Lost catch light detail 35 Missing reference file 35 The softw...

Страница 4: ...y be affected by scanner setup viewing conditions subject matter and user expectations For fine art reproductions and product photography the HCT provides a higher dynamic range and wider color gamut than typical camera targets so a greater portion of the camera s color space is characterized However as with all camera targets color matching quality is also affected by variations in lighting spect...

Страница 5: ...asured for highest accuracy 35mm targets are produced in very small batches on a sheet of 8 x 10 inch film Two 6x7 cm targets on the same sheet are measurement and averaged to produce an extremely accurate batch averaged data file for the whole sheet The HCT specification does not define colorimetric values for any patch but allows the widest dynamic range and color gamut possible with the base ma...

Страница 6: ...ng and or instrumentation differences Although reference data are supplied to three or more decimal places the least significant digits are uncertain and may be safely ignored by the profiling software Manufacturing date vs measuring date Batch dates marked on each target indicate the date of exposure and development not the measuring date Measurements are made as near as possible to the shipping ...

Страница 7: ...m X Rite i1Profiler 1 5 www xrite com X Rite EyeOne Match X Rite MonacoProfiler 4 0 X Rite MonacoDCcolor X Rite ProfileMaker 5 For latest additions and alterations to this list go to www hutchcolor com hct htm If your scanner or camera profiling software does not support the HCT please contact the manufacturer and or HutchColor LLC Trial software From time to time third party demo or trial profili...

Страница 8: ...ilure to observe these rules may lead to clipping or reversals in the profile CCD scanner evenness Flatbed scanners especially some 35mm slide scanners often suffer from uneven illumination across the image which will negatively affect profile accuracy To check for evenness scan a flat tint of evenly exposed slide film about 0 30 to 0 60 density and examine the RGB values across the entire area Va...

Страница 9: ...n and CAREFULLY remove any blemishes with the clone brush rubber stamp tool Be careful not to clone from one patch to another Most profiling software uses only the central 50 of each patch Ignore blemishes near the patch edge Blemishes outside the central 50 of each patch can be ignored WARNING Do NOT attempt to remove grain from the target scan e g with an anti noise filter Believe it or not a gr...

Страница 10: ...to creating the profile Precise cropping is usually NOT necessary in Photoshop If desired rough crop the target to about two or three patch widths larger all round The profiling software should ask you to locate the position of the target s corners with a cursor in effect cropping the target scan Cropping methods and tools vary but the HCT s cropping points shown below are the same for all softwar...

Страница 11: ...ensitivity to match the scanner s maximum shadow sensitivity Because most scans are adjusted to optimize the subject the net result is virtually the same as scanning a longer range target Add an Infinite density patch Prior to scanning the target add a double thickness of blackened film Silver tape or some other highly opaque material in the scan area to represent infinite black density Adding an ...

Страница 12: ...e R 21 3 17 G 22 3 18 B 17 3 14 In Photoshop s Levels control enter the smallest or the average of the R G and B differences in the top left box then click OK Extending shadow contrast in Levels Create an Extended profile Save the modified target scan with the suffix xt for extended Keep a copy of the original scan in case you want to modify the amount of extension in a subsequent profile In the s...

Страница 13: ...he HCT white patch past 254 If it does either reduce the amount of extension or change the scanner s RGB setup to get a lower RGB value in the HCT white patch then scan the target again Extending highlight contrast in Levels Note that if you scan both artwork and photographic prints you should make two profiles from the reflective HCT one for photographic prints with no extension and one for paint...

Страница 14: ...k too dark if seen on a light table The same thing happens when 4x5 or 8x10 inch transparencies are viewed inside a black mask For this reason a scanner profile that works well for 4x5 or 8x10 inch transparencies viewed on a light box with some surrounding area of white will usually SEEM too dark when used on 35mm transparencies or larger transparencies viewed inside a black mask The simple soluti...

Страница 15: ...rkening the blue channels RGB workflow but this is tedious and not practical if you scan a lot of Kodachromes Making a pseudo Kodachrome profile eliminates the need to edit each Kodachrome scan separately in Photoshop Requirements You will need a selection of sample 35mm or 120 slides on the emulsion you are profiling including some with large areas of grays or near neutral grays and some with lar...

Страница 16: ...y of the viewing booth or adjust the color balance of the monitor or re create the scanner and or monitor profiles until the displayed HCT scan matches the target as closely as possible Correcting gray balance Compare the displayed collage with the actual Kodachrome originals in terms of overall gray balance Ask yourself Is the screen image too red too yellow too green too cyan too blue too magent...

Страница 17: ...as closely as possible NOTE If you are not working with an accurately profiled monitor make some estimated changes then reproduce the collage on a profiled printer Compare the print to the collage in a viewing booth and repeat until the print is as close as possible to the original collage Modifying the HCT scan Once the Curves and Hue Saturation correction layers are adjusted optimally drag the w...

Страница 18: ...n the Hue Saturation 1 layer left and its inversion in the Hue Saturation 1 copy layer right Testing the inversions The whole point of the inversion process is to make the two Curves layers cancel each other and the two Hue Saturation layers cancel each other You can test this by toggling the Group 1 Set 1 eyeball on and off If there is no visible difference between Group on and Group off then the...

Страница 19: ...ctive NOTE The image of the HCT target should now look as if it had been created on Kodachrome film or whatever emulsion you are trying to profile Typically this means it will look bluer than the actual HCT transparency target in the viewer but the actual difference depends on scanner and film involved Flatten the HCT image Layer Flatten Image and Discard hidden layers Save a TIFF copy of the flat...

Страница 20: ...y making a printed reproduction and comparing it in a D 50 viewing booth to the original transparency collage Qualify the result by comparing a reproduction of the raw HCT image with the normal profile assigned to it If the results look good this is your Kodachrome profile or the profile for your specific emulsion type If you need to make more corrections go back to the layered HCT file alter the ...

Страница 21: ...pture compared to the profiling capture setup Copy work scanner on a tripod The simple goal in copy work or fine art reproduction is the most accurate reproduction possible where the camera is in effect a scanner on a tripod Copy work may require a custom profile for each individual set or setup but a single profile may serve indefinitely so long as the same lighting camera and camera settings are...

Страница 22: ... in glossy originals but it also poses a special challenge during capture For best results reduce reflections by as many of the following methods as possible Darken the location good first step whatever else is done Place the lights at a shallow angle to the copy typically 30 or less Narrowly baffle the lights to eliminate light falling on anything but the target Drape the camera with black velvet...

Страница 23: ...ghting evenness One of the most important requirements is even lighting across the target or more specifically across the image plane inside the camera Here are some techniques to ensure evenness With a stick or finger check that the shadows cast by each light in the center of the target plane are equal as shown in the following diagram If one shadow is darker than another move the light on that s...

Страница 24: ...uilt typically between 245 and 250 in all three colors When possible always shoot with the lowest ISO setting to reduce noise White or gray balance To ensure repeatable performance of a profiled camera white balance the camera whenever lighting filtration or the lens is changed The exception is when a filter is used for a special effect The method of balancing depends on the camera software Typica...

Страница 25: ...tops extend the black end to yield a long range of at least 8 f stops or more Although you may seldom use the extra range it s better to have it and not need it than need it and not have it If most subjects look a little flat or smoky in deep shadows it s a simple matter to correct this later in Photoshop But with too little shadow detail or not enough f stops deep shadows may plug in or block up ...

Страница 26: ... not be possible on some cameras Tweak the curve until it is almost a straight line with roughly equal separation throughout the scale but slightly less contrast in shadows Adjust overall curve height at the middle tone until patch L27 on the HCT measures somewhere between 100 and 130 in all colors Balance may be set one of two ways If there is no metamerism error between the target material and t...

Страница 27: ...as a the profile is sensitive to a full range of values from 0 0 0 to 255 255 255 and b you remember that the more you change the curve the less the profile will match the colors and contrast of the subject Note that for critical copy work or product photography any departure from the curve used when the profile was built will make it harder to match the original When evaluating the capture always...

Страница 28: ...iles html 4 View the image through the CMYK profile with Command Y 5 Create an adjustment layer for Levels and set the optimum white and black point of the image 6 If necessary create a Curves adjustment layer to lighten or darken or remove a color cast 7 If necessary create a Hue Saturation adjustment layer to correct specific colors 8 Save the RGB image with adjustment layers for use on subseque...

Страница 29: ...ay not look pleasing due to gamut limitations in the output device If at least one of the conversions looks like the target under proper viewing conditions D 50 transmission and overhead the scanner profile is probably good Repeat with live images If neither conversion is acceptable allowing for limitations in the output device there may be an error in EITHER the scanner OR the output profile We n...

Страница 30: ...ore of the scanner s RGB curves Inappropriate scanner response curve too dark too light or wrong curve shape Matrix or 3 D color processing in the scanner software prior to making the profile Optical flare in the scanner or camera system Color changes in the target caused by fading staining or mishandling Extreme gamut test Good profiling software should reproduce RGB values outside the gamut of t...

Страница 31: ...targets prior to scanning with a blower brush or oil free anti static brush Oily deposits or finger marks should come off with LIGHT PRESSURE from a clean lint free cloth and film cleaning fluid Be sure the fluid is intended for photographic prints Avoid polishing with harsh scanner wipes that may scratch the print s surface Water based cleaning extreme cases only WARNING This should only be attem...

Страница 32: ...rget You can test any scanner target that you have previously used as follows Scan the target on the same device you profiled previously with identical scanner settings Make a new profile using the EXACT SAME profiling software and settings as before In Photoshop assign the new profile to the target scan or to any typical raw RGB scan Assign the old profile and observe any change on screen If the ...

Страница 33: ...software Grainy or noisy scans Q Upon enlarging the HCT target scan I notice a lot of grain in the patches Should I attempt to smooth out the grain before creating the profile A NO Any grain you see is a normal product of film emulsions and or the scanner and is actually valuable in helping an 8 bit per channel scanner see more that the normal 256 tone levels Good profiling software will integrate...

Страница 34: ...st HCT design some of the patches that were originally gray have slight pastel color variations to improve profile accuracy in near neutrals Dark 35mm profiles Q Why do all my 35mm slides look too dark I followed the instructions exactly A Relax this is quite normal and no it is seldom a failure of the target or even the profiling software There are probably several factors at work First there is ...

Страница 35: ...rk very hard to ensure the HCT s white patches represent the lowest possible D min minimum density some originals may have an even lighter D min which may not be recognized by some profiles This may be caused by varying thickness or different plastics in the base You can solve this by extending the highlight range of the HCT target scan prior to making the profile See Extended range profiles Missi...

Страница 36: ...n This can be tested by assigning the scanner profile in Photoshop to the RGBXPLORER test image at www hutchcolor com Images_and_targets html The problem can be reduced by lowering the quality setting from 4 to 3 or 2 but with a subsequent loss of profile accuracy For best results use another software ColorBlind software problems in grays Q How can I reduce the gray balance error I m getting with ...

Страница 37: ...sm failure a largely unavoidable problem in digital photography that stems from differences between the colorants in your subject and the dyes in the target combined with camera filtration and lighting issues Try profiling and shooting under tungsten illumination It may be hot and slow but tungsten usually reduces metamerism problems ...

Страница 38: ...be accompanied by the target in its original packaging complete with serial number sticker Return shipping is payable by the client Minor design differences or cosmetic blemishes outside the working area are NOT covered by this warranty HutchColor LLC does NOT recommend or warrant any third party hardware or software used with the HCT Because ICC profiles are critically dependent on software and h...

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