Chasing the missing colours further

The mystery of the missing adobe colours turns out to be is as simple as understanding the Colour Space being used in the HSL sliders, some unfortunate naming, and confusion on my part. I have exhausted my way around bothLightroom and Photoshop documentation and on-line tutorials etc. I did find a few others asking similar questions and found a few also doing direct tests on Lightroom with colour charts (see my approach below). I still had that empty feeling I was misiing something important.

I decided to investigate the missing colours for myself, I took a series of of different colour wheels into Lightroom (below is a conventional painters colour wheel) and just played around with the Hue Sliders in the HSL panel of Lightrooms Develop Module. This can be a lot of fun and well as giving you a sound understanding of how the sliders work. I strongly recommend trying it out for your self.

What I discovered  was first that the sliders did actually cover the full Hue (colour) range. Adobe have provided 8 slidesr so they where spaced 45^o apart (ie 360^o/8). Also each slider has an adjustment  range form –100 to +100 which seemed to cover 3 or 4 segments on the standard 12 division colour wheel (shown below). There also appeared to be some overlap with the adjacent sliders.

The next bit of the analysis is just my approximation. I assumed that each slider goes half way to the next slider plus a bit (ie 45^o/2 = 22.5^o plus 10^o) Then doubling that for the full movement of the slide from minus to plus yield 64^o (32^o*2) which is inline with my observations above. Now things where coming together,  I could build the table below and work out the range of HUEs in terms of the angular HSL measure.  the –100 column if the anticlockwise Angular number (eg, –23^o) and the –100 column is the clockwise angular number (eg, +23^o), give the extent of that slider in terms of Hue.

Adobe Colour	-100	Hue	+100	Better Colour Name
Red	328o	0o	32o	Red
Orange	13o	45o	77o	Orange-Yellow
Yellow	58o	90o	122o	Yellow-Green/Chartreuse
Green	103o	135o	167o	Green
Aqua	148o	180o	212o	Cyan
Blue	193o	225o	257o	Blue
Purple	238o	270o	302o	Blue-Purple/Violet
Magenta	283o	315o	347o	Magenta

I also to a HSL Circle (colour wheel) on which our common colour names had been applied to given segments. The obvious feature is our colour names don’t forma linear arrangement around the circle. Some colours (eg Yellow) have narrow range while others (eg green have a very broad range) at least in terms of their name.

Suddenly some of my previous observations, like if I used the yellow slider it was more likely to adjust the grass and foliage than the orche coloured yellowed of bleached grass or rocks. That the reds were very sensitive to their sliders whereas blues and greens less so. I also have taken the opportunity to better name the colours of the sliders. Thus now the Orange slider (now Orange-yelloe and the yellow slider (yellow-green) might both be required to enchance of shift the Yellowness of an image. Admittedly things get a little complex when luminance is also considered, that can be a latter topic for a post, but for now a better understanding of which hues are affected is a big step in the right direction to understand how to control colour in your Photograph.

So in conclusion, rather than there being missing colours, I found the names the HSL sliders where given in lightroom had lead me to think back to a conventional colour wheel (3 primaries, 3 secondary and 6 tertiary colours, ie 12 colours). Instead I should have realized Adobe had split the 360^o of the HSL Hue Circle into 8 division rather than 12. C’est la Vie

#TheDress …as a lesson in white balance?

What a massive amount of the social web and the internet bandwidth has gone into the less than important discussion of whether #TheDress is gold and white or blue and black (or any other colour for that matter)
There is some science at play (ie most folk can see differences but are not so good at absolute colour) BUT I am amazed in the 100 or so tweets I scanned no one have mentioned the Colour Temperature of Light and/or White Balance. The original image looks ok but it has a slight blue tint and the highlights in the background are “blown out” (in photoshop jargon “clipped”). What you see depends on whether you use this clipped background as your reference white our interpret the dress background as white. I have seen the mauve/blue cast in shadows on images where the highlights are blown out many times and I reach for the White Balance (see below) but so many people are used to just looking at their (often tiny) screens in a variety of lights and screen intensities and probably desensitized to what is colour balanced and what is not.
Hopefully most photographers will notice this straight away. And fix the cast before it is published. If you don’t believe me try colour balance for yourself, you can get a copy of the image here. download it and look at it with your normal software (I’m using Picasa here and the white balance correction tool here is call Neutral Colour Picker. You click on the eyedropper and then pick a white or gray part of the image click on that and picasa then removes any colour cast. If I click on the base colour of dress notice it was warmed (added a yellow/brown cast to the background). The photographer took a photo of a white dress with gold strips, I do not doubt this for a moment.

Different software has different ways to do this and for example lightroom has the neutral tool eyedropper but it also an Auto White Balance button which is pretty reliable. A better place to start is in your camera. Get out your camera manual and work through colour temperature and white balance. Try out some of the setting and situations they are recommended. You will probably reach the same conclusion most other photographers have, set your camera to auto white balance and try to ensure the exposure is fine (no blown out highlights) Unless you think you need to do differently (ie you are shooting in a specific lighting condition with specific colour temperatures)

Postcript

Looks like I'm wrong, the whole photo must be overexposed, not just the background. The Dress is Navy & Black!

PhotoProject :: Photographing your Art Works

I have seen and read a lot about how to photography your art and/or why you shouldn’t. Most of it seems wrong to me, or at least all overly complicated. There is really no reason that your should not be able to get very good results, even with a mobile phone

Keep it Simple but Precise.

It really doesn’t matter weather you will be taking the photo with a very basic point and shoot camera, a smart phone or an expensive DSLR camera. There are a few basics you need to understand to get a clear, well exposed and undistorted image. Firstly you need to make sure that the art work is well lit by even light. inside that means on a wall opposite a decent sized window and out of direct light. If outside it may be better in the shade or waiting for an overcast day. If you want to use artificial lighting make sure you understand the next section. It is important that the artwork is normal (at right angles) to the axis of the camera lens. This gives the photo the best opportunity of everything being sharply in focus and avoids much of the possible distortion. Hanging or taping the work to the wall and setting your camera on a tripod of nearby bench can help you get this right. The camera should be pointing straight at the art work not pointing up or down. I have a nifty little level that plugs into my flash hot-shoe which makes checking the alignments very easy. The autofocus mechanism of most cameras are very reliable these days especially when you are pointing at a single subject in one plane. so I would suggest you go with auto focus, usually that requires half pressing the shutter key. The other important aspect about keeping the image clear is avoiding camera movement as you take the photo. If you have your camera on a tripod or sitting on a form service is is best to use the cameras timer. If you have to hold the camera try using the fastest shutter speed (better than 1/60 seconds). The next step is upload your photos to your computer, but leave the camera and art work set up. Whilst you can preview the photo on the LCD panel on the camera back you will be able to check details better on a larger screen. If something needs to be change everything is still set up.
There is a tendency to get as close as possible to the artwork and use the zoom in to get a wider angle view, However this can distort the edges of your work (they start to look curved) and introduce depth of field issue so that while the centre of the work is in focus the edges are not. Step back a bit use and no zoom or just a little zoom in (rather than out), or better still use the prime (single focal length usually 50mm) lens are this will be the least distorted. If the side of your art work diverge you are probably not alighted with the centre of the artwork and at right angle to it. It the sides diverge out and up you viewing angle is to low. If they diverge out and down you are to high, move the camera down a little Obviously curved edges you will be too close.
Normally it is best to photograph your art without a frame (unlike my example here) and it the art work is framed behind glass you will have to deal with the problem of reflections. The can generally be avoided by angling the light source. If you are using natural light that might mean angle the artwork against the wall, but remember to also tilt the camera so the axis of the lens is at right angle to the art works surface. If you are using artificial light use two but angled at 45degrees to the art work.

Strive for Accurate Colour

Colour is probably the area that most people stumble when photographing art. The auto exposure in cameras is trying to expose everything to an average grey, art work is usually move vivid and vibrant. Colour calibrated screens are not going to help if you have the white balance wrong. White balance is an attempt to make surethat parts of your subject that are white or close to white are also white in the photo. The temperature of light is quiet deep issues, and I will skip the theory here and just comment that different light sources (particularly artificial lights) can introduce significant colour casts into a photo. Most modern cameras do have white balance settings, typically marked sunny, overcast/cloudy, Incandescant, tungsten etc according to the light source some go further and allow you to adjust by the colour temperature (specified in digress Kelvin) of your lights (better brands of flash and strobe lights will give you these temperatures). If you suspect colour matching issues it will be best to do some test shots, such as including a colour wheel in the picture and look at these photos after you have loaded viewed them on your computer screen. Leave your camera set up and if necessary, make an adjustment, take a new photo, upload it and look at it. Once you are happy remove your colour test and take the final Image.
Cameras, computer screen, and projectors and printers are not capable of reproducing the full dynamic range of light our eyes are capable of seeing. Again this a deep topic and I wont cover it here, but adding a tiny amount of contrast and saturation in post processing may help lift the colours, but keep the image looking natural, particularly for smaller thumbnails of the work.
One final bit advice of colours, is for those that want to reproduce their work as a smaller thumbnail on a website for sale. Don’t get to carried away with colour management as it likely to make your photo image look dull when the viewed on typical users screens. When you want to prompt your art on the net have a look at your photo on a variety of screens and devices (for example colour calibrated images can look very dowdy on apples new retina screen which get a lot of their appeal from their rendering of saturated colours). If you are photographing your image to have it reproduced, such as printed on canvas or art paper (or even sold via Red Bubble etc) then of course colour calibration becomes very important.

Do Not Over Post Process

Whilst it is unlikely that you will want to “publish” your photo un-edited it is wise to consider that also keeping the post processing as simple as possible with  also be import. The key steps being crop the image to the edges of your work (that normally means don’t have boarders showing), perhaps some white balance adjustment (its better done in the camera, see above), a light tweaking of contrast (raising the contrast just a little) and possibly a very little lifting of colour saturation. However be retrained, some of the “zany” filters in phone apps and the filters on web album sites can go too far and ruin an otherwise honest photo of your art, moving any of the sliders too far to the right, in photoshop, lightroom, iphoto and picasa can also undo your good work,  If there are blemishes (like dust stops) retouch them out, but do not try and retouch things in the art work. Finally consider the size to export (small thumbnails for a web site or full size, high resolution for a canvas print). You don’t need elaborate software for these steps (for example Picasa, free to download, will do all these steps) or alternatively you can look at on-line apps like Aviary.

“Da Vagues”, pastel sketch on craftboard prepared with gesso and acrylic background paint. 20 by 45cm.

The following video, from YouTube, by does go through most of theses steps is a straightforward easy to follow tutorial by Tyler Stalman, of SatchiOnline.

Removing A Colour Cast

Having been inspired by a couple of pizza recipes on MasterChef, the results were worth a photo but alas under the halogen downlights (2,700–3,300 K) there was a strong orange colour cast. These downlights have a much lower colour temperature (those K numbers) than daylight (5,500–6,000 K). You can of course use the white balance setting in your camera and set it to artificial or tungsten. However I was hungry and just took the photos as they were. Not to worry most photo editing software will have the ability to make an adjustment for such colour bias as a post process. In picasa there is the nifty Neutral Colour Picker tool under the tuning tab. Click on the little eye dropper and them click on something in your images that you want to be white or a neutral grey tone. There is part of a cook book on the left hand side so I use that, and instantly the colour bias is removed although I also used both the fill light and highlight sliders to lighten the image a bit. An appetizing pizza bianca recorded for posterity!