How many shades of blue, did you say?
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DESCRIPTIONThese slides were first presented the Thurday 31st of Jul 2014 at Cambridge Darkroom's meetup (http://www.meetup.com/CambridgeDarkroom/events/173760452/) Why is it that the image on your camera's viewfinder is nothing like the one you see in Photoshop? How come this stupid printer doesn't get the colours right either? Jonathan has crafted for you some colourful slides to give you both theory and practical steps to maintain accurate colour throughout the digital workflow - from camera to print. Although PS will be used as an example, the principles and steps are applicable to other workflow environments. Author Jonathan Beattie
<p>Created by J.Beattie 2014 Cambridge Darkroom Meetup Date: Thursday 31st July 2014 Slideshow Version: 1.0.1 Any images used are the sole property and copyright of their owners. All references to names and products are to be taken at face value and with the good intention intended. . Any mistakes are my responsibility and do not reflect any references, sources or people I have named or used. Don' take my word for it, there will be mistakes in this, do the research use this as a guide. Now, stop reading this and just go and take some photos! I am not a Colour Management maven There is a vast pool of knowledge at the meetings, we should learn to use it. Ask questions Don't ask, don't get If I don't know, someone else might If no one knows, I'll find out and get back to you Lot to get through I will take a break you'd be as well too as well Feel free to contact me through the Meetup group or via Flickr. If you have any ideas for future Meetups, add them to the group area on the Meetup site. Similarly, if you want to talk or present something, let the organisers know. If I can do it, you can do it! Always want to hear your feedback provide it on the MeetUp Page or contact me directly. It's a big subject so I will just be giving you the basics. - Understand basic concepts of colour. - Gain general and fundamental knowledge of colour management. It can seem daunting, but if you understand the basic concepts it becomes easier to understand. There is not a single solution, each person has different needs and requirements. - There is no blue pill! For some, there is no need to worry about it. It's worked so far and it will continue to. Others have noticed a change in colour and are frustrated and want to change it. Others still, have a professional need to reproduce colours as defined by the client. Hopefully these slides will be of enough interest to make you look at what you are already doing and if you change anything you will notice a difference. For others I hope it will affirm what they are already doing. Hopefully in a few years you will not need any need for this/. Things are getting much better. - Colour Management is being taken more seriously - Software has improved ad continues to do so - Printers/inks are better than ever and are getting better all the time Slides will be made available. - PDF version with these notes pages Apropos of nothing.. 10 Reasons to upgrade to PS: 1. Complicated Object Removal & Movement 2. Sophisticated Retouching 3. Complicated Selections 4. Merging Multiple Exposures with HDR 5. Merging Photos into a Panorama 6. Wide Angle Perspective Correction, New in CS6 7. Creative Compositing 8. Applying Artistic Filters 9. Designing Brochures, Business Cards, Posters, and Other Graphics 10. Video Editing Capabilities All devices render colour differently. Devices can only represent colour that is within their Gamut - Gamut is just the range of colours that can be reproduced For example: - Printers can interpret colours differently - 10 printers = 10 different colour prints - some printers can't print some colours, colours that are outside their gamut Colour Management is output centric - Luckily we all want to show our work, be it print of online. Can also help staying faithful to the colours of the subject - that might be a more artistic choice though and is best left up to the individual. RGB & CMYK are device dependent Devices gamut/colour-range The Butters Part 1 but I see colour all the time - Yes, but you are not seeing the same colour - perhaps the lowest common colour denominator just happens to work for you - that time! - because colour is subjective, I'll not see what you see - It might not work if you send it to a different printer All workflows can be broken down to: Image input image processing image output Many devices are improving their colour management - Mainly output devices: monitors and printers - Processing software is improving as well - Even low end software has some colour management There is a growing awareness of colour management - Hence this talk :-) You can manage a number of things: - Camera-MonitorWorkspaceSoft Proof-Printer 8-Bit: 2^8=256 colours per channel 256x256x256=16777216 colours per 8-bit file 16-Bit: 2^16=65536 colours per channel 65536x65536x65536=281474976710656 colours per 16-bit file Photoshop only allocates 32,769 levels to a 16-bit file (which is 15-bits plus 1 level) does this to simplify the math and processing. These huge numbers are definitions, not perceived colours, You cannot tell the difference between RGB 0,1,0 and RGB 0,1,1. Additionally editing changes the number of available colours through compression and tone mapping. 7 CMS Colour Managed System Input Devices Camera, Scanner, etc Output Devices Monitor, Printer, Press, etc 9 CMS is just an environment a practice CMM is embedded in processing software - PS, LR, Camera Raw, Aperture, PSE, etc - They all have some sort of CMM in them - Mac OS and Windows also have in-built CMM's - Meaning it can be at the system or application level Device profiles called ICC profiles - International Color Consortium - Different profiles types available - See http://www.color.org for more details A profile is a set of mathematical measurements that define reproduction of colour for a particular device Device independence means that the colour space can be defined and measured completely independently of any device. This replication capability is at the heart of CMS The ability to map colours from one space to another in a known and predictable manner Some Device Independent Colour Spaces AdobeRGB, sRGB, ColourMatchRGB, BruceRGB Closed Environment all inputs and outputs are managed. Device independence means that the colour space can be defined and measured completely independently of any device. This replication capability is at the heart of CMS The ability to map colours from one space to another in a known and predictable manner Some Device Independent Colour Spaces AdobeRGB, sRGB, ColourMatchRGB, BruceRGB Mac has system level CMS ColorSync Defaults to Heidelberg CMM Can be configured to use other CMM's Win XP onwards uses CMS ICM2.0 Defaults to Heidelberg CMM Adobe products have their own in-built CMS PS defaults to Adobe (ACE) CMM Option to use system level CMM Can be configured to use other CMM's 11 The Butters Part 2 but I only use B&W - A colour managed workflow provides accurate tone rendition - Provides the truest B&W accuracy - Allows you to produce more neutral B&W images Really only matters to those that are really fussy about their tonal values. Your monitor and printer still need to have device profiles for accuracy. In camera conversion provides no control over the conversion process. Sometimes it's necessary to boost (saturate) colours before conversion to get the desired effect. You have all that data, why would you through it away? The 3-channels proved data you can use to influence the conversion - this is how the channel mixer conversion works. Obviously your are not shooting in Jpeg! Use in camera to just get a feel of what it will look like in B&W then shoot normally anyway. The RAW file will still contain all the colour data - Unless you have the Leica M Monochrom - Camera porn time --------------------------------> There are books devoted to the subject There's plenty of maths and physics in it - if that floats your boat Don't lose sleep over this.... Goodnight, sweet prince/and flights of angels sing thee to thy rest - from Hamlet by William Shakespeare Visual Spectrum 16.7 million Colours Human Eye 10 million (I've read this figure as being anywhere from 8-12 Million) Pre-press 70K Colour models typically use 3 or 4 numbers (tuples) to represent a colour. A Tuple is a set of numbers to describe something. Greyscale can also be thought of as another colour model HSB variants HSL, HSI, HSV Brightness variants Lightness, Intensity, Value All the same thing really There is also Spot Color in offset printing where colours are defined and mixed beforehand. Many names for these defined colour sets - Pantone Matching System(PMS), ANPA, DIC, FOCOLTONE, Hexachrome, HKS, TOYO, etc Art classes use Red, Blue and Yellow in reality, the pigments are closer to Magenta and Cyan, i.e. additive. RGB = Red Green Blue Green has more luminance because of how the camera works look at Bayer Filter for more information on how camera sensor allocates R (25%), G(50%) and B(25%) colours. The Foveon sensor does it differently and is found in Sigma cameras. RGB is how the 1st colour image was made by Clerk Maxwell 3 coloured light sources RGB colour requires light to be transmitted (added). RGB is a way of describing colour, it is not a colour or colour profile Sony Exmor uses different technology as well. CMYK = Cyan Magenta Yellow Black Each dye/ink absorbs (subtracts) light illuminating it and only reflects the components of its own colour back to viewer. Without light, there can be no colour. In a darkened room does colour cease to exist, or is it merely invisible? Discuss! CMYK is a Device Dependent colour since each printer will produce a colour space different to another. Some variables: Absorption of ink on the paper Ink texture and viscosity Ink formulations Surface texture of paper Application method 210 Dollops of ink without Black, but only 110 Dollops of ink with Black. A 100 Dollop saving bargain! Dollops could be thickness as well. Black used in printing as an ink replacement either as: UCR Under Colour Removal Works on Neutral Areas where CMY values are about the same GCR Grey Component Replacement Changes areas that are CMY equal uses less ink but shadows become flay and thin Alternative way of thinking about Additive and Subtractive: For RGB to make CMYK yellow: Need to add R & G For CMYK to make RGB yellow: Need to subtract M & C Photoshop and all processing software base their Colour Wheel on colour being mixed with light, i.e. Additive which we now know is RGB Colour wheel creation has itself become an art form. There are many styles, but all still hold the same basic colour principles. The PhotoShop Color Picker also gives the HTML # value basically the Hex value of the 3 RGB Tuples. Elements only shows HSB & RGB Macs have all available in the Color Picker HSB 0 degree and 360 degree is red A profile is a set of mathematical measurements that define reproduction of colour for a particular device CIE is the authority on light and colour. First mathematically defined spaces. Derived from visual experiments and represents nearly all the colours a Standard Observer can see. LAB now used as the internal space for PS Designed specifically to ease conversion between spaces (mathematically). All are actually 3D these are slices and show mid tones. CIE colour spaces - CIEXYZ - CIELAB Key space, not perfect but good - CIECAM02 - CIELUV - CIEYuv - CIEUVW - CIERGB CIELAB and CIELUV are known as Uniform Colour spaces CIEXYZ and LAB are the two main ones we as photographers need to worry about Same colours, just distributed differently. Frequency from the spectrum image follows the curved edge. The X and Y axis represent unity values to allow a colour to be represented. There is also a Z axis (not shown) as these are all actually 3D representations. This shows a 2D slice across what we wold know as the mid-point 3D representations are given later in the presentation. CIE defined. Sometimes marked as 'E' to represent the equal-energy point. Originally temperature values were 500K, 5500K, 6500K and 7500K until Planck's Law was revised by the science community. Still often see them as these rounded values and easier to remember. D50 and D65 are the ones you might hear about. Only mentioned in case you are ever asked to select D50 or D65 - D65 will be the most commonly used one to select. Defined as the radiation from a BlackBody, but these measurements are not from a perfect blackbody as these based on atmospheric filtered daylight. D-Series developed in the 60s (published in1964 I think). There are A, B, C series before now deprecated, and E, F after. Each series is specific . We only care about the D series. Moves along the black line from a couple slides back. Absolute colour space: A colour space in which colours are unambiguous - where the interpretation of colour in the space is colorimetrically defined without reference to external factors These are the most obvious, popular and used. Universally recognised. There are many more obscure and obsolete variants, including some highly specialised ones. There are colour spaces specifically used for face recognition Panatone have their own colour spaces Technicolor used to have one for their old film stock There are other colour systems as well (Munsell for example) Device Independent spaces sRGB THE standard RGB colour space Created by HP and Microsoft (1996) Designed for use on monitors, printers and for the Internet. All hardware now offers better colour spaces Only now are we beginning to move away from using it on the Internet Uses D65 Illuminant Point Uses an approximate 2.2 gamma Adobe RGB (1998) Sometimes called Adobe98, but mostly AdobeRGB Improves the gamut over sRGB - mainly in the Cyan/Green region Big difference in shadows and highlights over sRGB Uses D65 Illuminant Point Uses a 2.2 Gamma ProPhoto RGB Usually just called ProPhoto Developed by Kodak Covers 90% of LAB colour Some colours represented are imaginary (the ones outside the spectrum) Uses a D50 Illluminant point Uses a 1.8 Gamma Amaze your friends with the fact that sRGB is also known as sRGB IEC61966-2.1. ProPhoto requires you to edit in 16-bit 29 30 You could create your own - if you want to, ask someone else! ICC Defined Device Independent spaces Create your own space Device Independent Profile - Camera Device Dependent Profile - Monitor Calibration Device Independent Profile - Processing Software Device Dependent Profile - Printer - Soft-Proof - Web Output 33 If you shoot Jpeg definitely make sure you set the in-camera colour space and keep the EXIF. We can override the embedded in PS Make sure you embed the profile in Jpeg's, even if you dump the Exif You should le be keeping the Exif just for Copyright if nothing else. Refer to your manual for how to set the colour space Id recommend the highest colour space your camera supplies. If your camera has ProPhoto you should be editing in 16-bit anyway. Remember though, shoot RAW! If you do shoot RAW, when it comes to importing your images into LR/Camera RAW, or whatever your processing software is, you cam select the colour space to allocate. See next slide for an example. 34 The image shows the X-Rite ColorChecker Passport (50+) Supposed to shoot the card under known lighting conditions and those conditions you wish to profile Profile resides in your import processing software similar to the Camera Calibration Develop Box in LightRoom Not something I know a...</p>
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