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September 2019

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September 2019 photo & video Image 1: Opening the RAW image file in Adobe Photoshop Text and photos by Rico Besserdich When it comes to final editing of your digital underwater images, the white balance should be the first step of your digital post-production workflow. Always. What is white balance? Different light sources produce light with slightly different colour Adjusting tints. Think about sunlight, your camera’s strobe or underwater video lights, for example. By adjusting the white balance, we tell our cameras or imaging software which area of the photo White Balance is supposed to be white or neutral in Post-Production of Underwater Images grey. This step of editing removes colour casts, and as a result, displays your image with natural balance during post-production shooting in ambient light (using one should better not expect source. most macro shots) often require colours. requires a sufficient amount of no strobes or any other light to be able to restore colours When using underwater only minimal white balance What is important for light (colour information) to be sources other than sunlight). As of underwater images taken in strobes, it is a different story. adjustments—sometimes, none underwater photography is that existing in the (original) image. colours do fade away with the deeper waters (10m and more) Underwater shots that are entirely at all. However, the moment two a successful adjustment of white This is especially important when increasing depth of a photo dive, using sunlight as the only light lit by a strobe or flashgun (i.e. or more different light sources 83 X-RAY MAG : 93 : 2019 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO photo & video Image 2: Importing the image file into the Lightroom catalog are present in one image is the moment a colour cast will show up. In underwater photography, we have to deal with a cyan colour cast most of the time. This can be fixed by adjusting the white balance during post- production. What we need: • Photographs in RAW or DNG format. Those are the only formats that give you the opportunity to adjust the white balance after you take the shot. If you shoot in JPG, you hadbetter go for a manual white balance in your camera. This tutorial utilises Adobe Sea, Egypt. Depth: around 8m. Lots of fancy sliders here, but we white balance), and I think we balance presets (such as “auto,” Lightroom (LR) and Photoshop Light source: one 2500-Lumen only need the white balance can agree that something needs “daylight,” “cloudy,” etc.), • A colour-calibrated computer (PS). In terms of editing RAW video light, plus some ambient section, found at the top-right to be fixed here, as this image but those rarely work well with screen. Proper monitor images, Photoshop’s ACR (Adobe light from the sun. corner of both programmes. (See suffers a serious cyan colour cast. underwater images. So, let’s leave calibration will ensure that your Camera Raw) and Lightroom Images 3 and 4) ACR and Lightroom offer a the image as it is: “as shot.” colours and black levels are are based on the same software In Photoshop, open the RAW In this example, the camera couple true, which is crucial for proper engine. The only difference is the file in ACR by double-clicking in was set to “AWB” (automatic of white image editing and for later user interface. Adobe Bridge or by dragging and printing. dropping your RAW file on the Note: It is not necessary to own Photoshop icon. Photoshop starts • An image editing software the newest versions of PS and/or and ACR pops up. (See Image 1 that is able to process RAW LR; older versions work fine, too. on the previous page) (or DNG) images. Adobe Photoshop or Lightroom are Adjusting white balance In Lightroom, import the image the classics here, but any RAW In this tutorial, we are using into your Lightroom catalog by processor can do the job, the example of an image of a using the import option. (See even the (free) one on your yawning lionfish from the Ras Image 2) camera’s software CD-ROM. Mohammed National Park, Red Image 4: White balance sliders in Lightroom Image 3: White balance sliders in Photoshop 84 X-RAY MAG : 93 : 2019 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO photo & video Image 6: How the image looks after using the white balance col- our picker. The cyan is gone but there is a bit too much magenta. The tool offers us a colour worries, going back to picker, a slider for the temper- “as shot” always brings ature, and a slider for the tint. you back to the original “Temperature” defines the colour state of the image. temperature in Kelvin. This slider What is important here is goes from blue (cold light) to developing a sense for yellow (very warm light). “Tint” the colours by watching defines the colour range between the change of the finest green and magenta. Slide the details very carefully. sliders and see what happens. No And then there is the colour picker. Let’s start with that be (more or less) white. I use too much magenta in it. one. Using the colour picker, you the colour picker and just click In this example, we just need basically click on an area in your somewhere on the area of the to move back the tint slider a photo that is supposed to be fish’s lips. (See Image 5) bit. Remember, this slider adjusts white or grey. It comes in handy The red circle indicates the colours from green to magenta. here to be able to remember area where to do a pick. In some After using the colour picker, what should be white (or grey) cases, several attempts are the tint slider went to “+150”— and what should not. needed to achieve a pleasing obviously, too much magenta. I recommend using the colour result. See Image 6 for how the Moving it back to around “+1242 picker for a first “rough mix” and picture looks after using the white fixes the problem here. Now, you then doing the fine adjustments balance colour picker. can move the temperature slider by using the temperature and tint The cyan colour cast is gone, a bit, making your image look sliders. and the colours (and thus the warmer or colder. That is totally Getting back to our yawning overall image) look better already. up to you and how you want your lionfish—as I recall, the “lips” But looking carefully at the image, image to look like. I leave it here of that fish are supposed to we notice that there is now a bit at the “picked” value of “11750.” Image 5: The red circle indicates the area to do a colour pick, which should be white (or gray) 85 X-RAY MAG : 93 : 2019 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO Tip of the Day by Peter Symes photo & Are your colours off? video There is a simple way to check whether your com- puter monitor repro- duces the colours of photographed subjects with rea- sonable fidelity. Calibration devices Professionals and other serious users will know about col- our profiling and calibrating all of their equipment, and using a colour-balanced workflow throughout, for consist- ent and accurate results. To ensure correct calibration of monitors and printers, calibration devices have to be used. Professional-grade monitor calibration devices, such as X-Rite i1Display Pro, Datacolor Spyder or ColorMunki, will set the user back some $/€ 200-300, with colour target charts includ- ed. And then a proper wide-gamut monitor should really be used, which may be an additional and more substantial investment. The casual shooter may not want to go down that road just yet. There is an easier, and much cheaper, way of checking a computer monitor’s fidelity and making some adjustments for a better match between rendition and the original subject. Colour charts and underwater cards The credit card colour chart shown is a ColorChecker ren- dition card seen on Amazon for about US$/€ 20. There is a reason why these specific colour patches are used, but that will be a story for another time. Suffice it to say, this chart represents a standardised set of colours, and the card is a reference we can easily carry with us in the field, and even Image 7: “After” shot. This is how the image looks after the white balance correction in post- underwater if the card is plastic. production is completed. When shooting a series of images, start by taking some test shots in which the card is placed somewhere in the scene Now, the image looks like this. (See Tip 2: When placing the white balance where it is clearly visible. Once back at your computer, you image 7) picker tool on parts of your image, PS and can then directly compare how the colours on the card in LR always display the RGB values (right the images are rendered on your monitor to the colours on Tip 1: When PS or LR displays extreme below the histogram) of that specific the physical card, which you can simply hold up beside the high “temperature” and “tint” values area. If the value shows “255, 255, 255,” monitor. (temperature at or near 15,000; tint this means that a pure white already exists Any discrepancies in colour reproduction and white balance at or near 150) after applying the in the image and not much can be done will immediately stand out, enabling you to make some appro- above-mentioned technique, this often regarding white balance.
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