Photography in the RAW

The Royal Photographic Society Imaging Science Group

Good Picture - 2007

Dr. Harry Adam & Dr. Tony Kaye

Good Picture - 2007

What is RAW?

What is Cooked?

RAW or Cooked?

RAW is the digital equivalent of a latent image

RAW = Undeveloped

Product photographers using sheet film often made multiple exposures at the same camera settings giving several identical latent images so they could be developed in different ways. A single RAW file can be developed an infinite number of times (and ways)

Digital sensors (pixels) simply measure light levels, expressed as voltages and converted to one of a discrete number of levels for digital representation.

Colour interpretation depends on the filter array used in the specific camera and on software to interpret or interpolate the colours not actually measured at a given pixel.

A filter array commonly looks like this - the Bayer pattern (Kodak patent to Bruce E Bayer in 1976, US3,971,065 )

So what? Well, colour, tone-scale and other factors set by the camera are now cooked. Worse - normally a low-bit, compressed file (jpg) is created.

8 bit images: 28 levels = 256 levels 16x levels

12 bit images: 212 levels = 4096 levels

14 bit images: 214 levels = 16383 levels

16 bit images: 216 levels = 65532 levels

RAW

Scene Modes Colour preferences White balance Sharpness Noise reduction

Storage space…?

Not an issue…………….

16 Gb Sandisk Extreme III CF - £159 inc. Vat (7/12/07) 2 Gb Sandisk Extreme III CF - £18 inc. Vat (7/12/07)

500GB external HD - £65 (7/12/07) – smaller than a 100 slide tray/box – and each of those cost over £10 10Mp Olympus E3 gets 98 RAW +jpg on a 2Gb card Film - £10 for 36 exposures? 98 images = £27

Workflow??

RAW, RAW + jpeg

~3 Mp jpg embedded in RAW use free exiftool to extract – ideal for web applications.

Over to Tony to tell you more about choices of developing your RAW files.

 It is often argued with considerable truth that the number of developer formulae published in the Almanac and other standard works of reference is far in excess of that required by the average photographer.  Indeed, it is quite possible and successfully practical regardless of subject to carry out the development of all types of plates and films, and further to make the necessary prints on any type of modern developing paper, using a single well-balanced M-Q developer of the Ilford ID-36 or Kodak D-158 type.  How then do we justify the array of formulae, relatively small though it is...... First must be considered the newcomer to photography, who regardless of sound advice will be tempted to experiment with almost every formula which comes his way. Secondly, there is the expert who desires to find always his favourite formula in the current Almanac, and at the same time be apprised, particularly in the case of fine grain developers, of any change that has taken place in developing technique.

 A raw converter is a “digital developer”

 Silver Halide Latent Image

 D76, ID11, Acutol, Promicrol, Microphen, etc.  Digital Camera RAW File

 Adobe, Bibble, Corel, Nikon, Canon, etc.  From the RAW data

 Read camera metadata  Demosaicing (Bayer Array)  Colour Balance (white balance)  Tone scale  Colour Reproduction  Noise Reduction  Sharpening © 18/12/2007 – Dr. H. Adam & Dr. T. Kaye What Software/Converters? Nikon D70 Nikon D200

Camera Colour Image Camera Colour Image metadata Managed Size metadata Managed Size

In Camera Processing √ EXIF in Jpegs 3008 X 2000 √ EXIF in Jpegs 3872 X 2592 Adobe CS3 Extended ICC 3008 X 2000 ICC 3872 X 2592 V10.0 X X Bibble V4.9.8e X ICC 3028 X 2002 X ICC 3880 X 2608 Capture One V3.7.7 X ICC 3008 X 1996 X ICC 3872 X 2592 Corel Paintshop Pro XI ICC 3036 X 2010 ICC 3900 X 2612 V11.2 X X DXO Optics Pro V5 Some ICC 3008 X 2000 Some ICC 3872 X 2592 FastStone Image Viewer EXIF 3039 X 2014 EXIF 3900 X 2616 V3.1 X X IrfanView V3.99 √ X 3008 X 2000 √ X 3872 X 2592 Nikon Capture NX V1.2 √ ICC 3008 X 2000 √ ICC 3872 X 2592 Picassa 2 V2.7.0 X EXIF 3039 X 2014 X EXIF 3904 X 2616 © 18/12/2007 – Dr. H. Adam & Dr. T. Kaye What Software/Converters? Kodak P880

Camera Colour Image metadata Managed Size

EXIF – In Camera Processing √ 3264 X 2448 JPEGS/TIFFS Adobe CS3 Extended V10.0 X ICC 3264 X 2488 IrfanView V3.99 √ X 3264 X 2448 Kodak Easy Share V6.4.0 √ EXIF 3264 X 2448 Picassa 2 V2.7.0 X EXIF 3280 X 2454 Bibble V4.9.8e N/A N/A N/A Capture One V3.7.7 N/A N/A N/A Corel Paintshop Pro XI V11.2 N/A N/A N/A DXO Optics Pro V5 N/A N/A N/A FastStone Image Viewer V3.1 N/A N/A N/A

Dark Light Blue Foilage Purplish Bluish Skin Skin Sky Blue Green

Orange Purplish Moderate Purple Yellow Orange Blue Red Green Yellow

Blue Green Red Yellow Magenta Cyan

White Neutral Neutral Neutral Neutral Black 8 6.5 5 3.5

 The test chart was photographed

 Nikon D70 & Nikon D200 - RAW & High Quality JPEG  Kodak P880 - RAW & TIFF  Custom White Balance, normal/standard for colour saturation, sharpness, contrast etc.  sRGB colour space selected  Opened using all the different converters  Default settings for colour, noise reduction etc.  Saved as 8bit TIFF sRGB  All images opened using Photoshop CS3 Extended

 Custom action used to record r,g,b code values from all patches  Values saved as text file © 18/12/2007 – Dr. H. Adam & Dr. T. Kaye Colour & Tone Scale - Data Analysis

 Text files imported into Excel – Macros used to:-  Convert r, g, b code values to L* a* b* (Lightness, R-G, Y-B)  Correct residual lightness and colour errors so the mid scale gray (N5 ) values match the reference values for the chart  Compare the L* a* b* values of the data from the files with the reference values of the Macbeth Chart  Calculate CIE 2000 colour differences  Data plotted  Colour Balance  Lightness  Colour Accuracy  Colour Saturation

Capture One Bibble © 18/12/2007 – Dr. H. Adam & Dr. T. Kaye Tone Scale D70

Bibble Corel PSP

Bibble Adobe

Adobe IIIa

Picassa IIIa

© 18/12/2007 – Dr. H. Adam & Dr. T. Kaye Noise - Data Acquisition & Analysis (I)  Exposures as per colour reproduction  Nikon D70 & D200 ISO 800  Kodak P880 ISO 100  Opened using all the different converters at default settings  Saved as 8bit TIFF sRGB  All images opened using Photoshop CS3 Extended

 Correct any residual lightness and colour errors so N5 from capture matches reference L* a* b* values for the Macbeth Chart  Converted from sRGB images to Lab images  Histogram function

 Rectangular crop used on N5, N3.5 and Black  Standard deviation recorded for L, a, and b  Averaged over the three neutral patches  Luma Noise – standard deviation “Lightness”  Chroma Noise – (standard deviation a2 + standard deviation b2)1/2 © 18/12/2007 – Dr. H. Adam & Dr. T. Kaye Noise - Data Acquisition & Analysis (II)

FastStone Capture One Capture one + NR

8 X 8 Blocks – JPEG?

 Dramatic colour saturation difference between Nikon D70 & D200  Only small/minimal differences seen with other converters  Why?

 Sorry we ducked the issue!!!  Star chart gives a subjective comparison of resolution  Sharpness is visual attribute

 Depends upon viewing distance type of output etc.  Easily changed via USM  Difficult to show on a projection system

 High quality digital output needed

 Sharpening needs to be fine tuned for output

 Deciding to shoot RAW defers image decisions to you, but......  1 RAW file, 10 converters  10 Different images!!  RAW converters really are like “devlopers”  1 Film Type  10 Different processing labs or “developers”  10 Different results

 Late breaking test on Corel Paint Shop Pro X2  Colour & Tonescale = Paint Shop Pro XI  Demosaicing – equivalent performance to XI  Late breaking test on Irfan View 4.1  Colour & Tonescale = Version 3.99  Demosaicing – equivalent to Version 3.99  JPEG artefacts present in both 3.99 and 4.1

 Download the “DEMOS” and try a few!  Make certain the software will open the RAW files your camera generates  You may decide ease of use and workflow takes precedence over “quality” or features  Colour, Tonescale, Sharpness, Noise  Adjustable via filters, levels, curves etc.  Demosaicing artefacts  Difficult if not impossible to eliminate in a fully “rendered” image

What RAW Converter should I use?

I don’t know but try before you buy