D-Photo 63 out Monday

Cover 63
Time to get in that summer state of mind; the final issue of D-Photo for the year hits shelves on Monday and it's packed with stunning imagery and helpful tips for shooting in the summertime, capturing candid holiday moments, perfecting your family photography, and all the best photo gifts for the Christmas stockings.

Here's a taste of what's on offer this issue:

D-Photo Christmas Gift Guide: the best photography gifts for all budgets, from cameras and accessories to Christmas card printing and workshop vouchers.

Richard wood

Richard Wood

Portrait of a champion: portrait artist Richard Wood tells us how keeping the creative wheels spinning helps overcome the daily grind and produce award-winning images.

Meet the scholars: take a look at fresh work from 11 of New Zealand’s most promising up-and-comers.

Craig Levers

Craig Levers

Summer photography: sun-loving photographers Craig Levers, Tessa Chrisp and Stephen Robinson share their unique approaches to capturing a Kiwi summer.

Authentic family photos: top family photographers Holly Spring, Karyn Worthington and Anna Munro teach us to get warm, creative shots of the whānau, be they formal portraits or casual family gatherings.

Karyn Worthington

Karyn Worthington

Arctic adventure: travel photographer Chris McLennan crosses another location off his to-do list as he turns his lens on the Arctic’s polar bears.

Shoot your Christmas cards: local legend Jackie Ranken busts out the family album to look at different approaches to holiday portraits.

Tropical traipsing: Andy Belcher cranks out one of Nikon’s latest goodies in beautiful Niue

Paul Petch

Paul Petch

Good with children: Paul Petch looks at eight simple tips to get your head in the zone when tackling the boundless energy of youth on a shoot.

Ring flash basics: Luke White explains the many and varied uses of a ring flash, from distinctive portraits to macro work.

Generation why: Mareea Vegas talks to emerging photographer Fraser Chatham about the new breed of 'hybrid photographers'.

Fraser Chatham

Fraser Chatham

Better group shots: Mead Norton solves readers’ common problems with the family portraits.

Sketchy: Hans Weichselbaum walks us through the digital editing process of transforming a photo to a pencil sketch

Head to your local newsagent come Monday for all that and much more in D-Photo 63, or pick up a copy online here.

Layer blending modes

01 - Blending Modes MenuDigital editing expert Hans Weichselbaum brings us the first half of an in-depth look at blending modes

Everybody working in Photoshop will be familiar with layers. After all, they’re one of the many assets of this program, but very few users take advantage of the layer blending modes. In general, there is more than one way to achieve a certain outcome in Photoshop, but quite often a simple change in blending mode, perhaps in combination with a layer mask, can get you there quicker and with less effort.

Here, I run through most of the available blending modes, with a short description of what each does. In a follow-on article next issue I will show you how to make use of blending modes in your day-to-day photography. Editing programs other than Photoshop (Corel PaintShop Pro and Photoshop Elements, for example) also use layers and blending modes.

Perched near the upper-left corner of the Layers panel you will find the pop-up menu for blending modes with a long list of choices.

Open an image, duplicate the layer, and then use the keyboard to cycle through the blending modes: press and hold the shift key then tap the plus key to go forward through the blend menu, and use shift and minus to go the other way.

You’ll find blending modes all over Photoshop, for example in the Layer Style dialogue box, with some of the filters, and in the Fade dialogue box. Some tools also make use of blending modes, including Brush, Paint Bucket, Healing and Cloning Brush, Gradient, and Smudge.

If you are working on a single image, rather than a composite of two or more images, then it’s better if you use an Adjustment layer instead of duplicating the image layer — it won’t double your file size. Simply put an adjustment layer on top of your image — it doesn’t matter which one you choose — and change the blending mode.

Looking at the long list of options, you might notice Photoshop groups them into six clusters. The default setting is Normal, and this behaves as you would expect when you put one image on top of another: the top image simply covers the one underneath, like a sheet of paper. If you change the blending mode to anything other than Normal, Photoshop applies some maths to change the appearance of your image.

I will demonstrate the various blend options with two layers: a blue sphere on top, and two red gradients in the bottom layer.

02 - Blending Modes

Image 2 — The two layers used for my demonstration

The first group: Normal and Dissolve

These two modes are at the very top of the list. We just looked at the Normal blending mode, which basically does nothing — there is no interaction between the active layer (the one you have selected) and the one underneath. Of course, you can still reduce the Opacity of the top layer to make it semi-transparent and let the image underneath shine through. Reducing the Opacity is also the way to go if the effect of one of the blending modes is too strong.

The Dissolve blend is quite unique, and there are not many applications for which you will find it useful. Most of the time you won’t see any change in the image at all. That’s because this mode only affects transitions between opaque and partially transparent pixels in the top layer. To make the effect visible I had to reduce the opacity of the top layer (I used 70 per cent). The texture effect is similar to what you often see as a transition effect in slide shows.

03 - Normal & Dissolve

Image 3 — The Normal (left) and Dissolve (right) blend options

Darkening modes

The members of the next section of blending modes all have a darkening effect.

04 - Darken Modes

Image 4 — The darkening blending modes

White is the neutral colour for all these blending modes. The effect is that any areas of white in the upper image will disappear, showing the colours of the underlying image.

The first mode of this group is simply called Darken. I didn’t include it with the examples shown, because its effect comes up as very similar to the Multiply blend. The Multiply mode multiplies the pixel values from the two layers, and then divides the product by 255 to normalize the value, getting it back into the allowed range. Think of two slides sandwiched together and projected from one projector. Perhaps that’s a difficult thing to visualize for the new generation of digital photographers, but take my word for it, the result will be a darker image. In practice you can use the Multiply mode to add density to an image that is too bright.

Colour Burn involves some complicated maths. Similar to Multiply, it darkens and increases contrast in the underlying image, then applies the colour from the upper layer to the bottom image, but as a function of how dark that colour is. When you use it on a layer filled with 50-per-cent grey, it intensifies the colours on the layer below. You can use it to fix an ugly sky in a hurry.

Linear Burn is a combination of Multiply and Colour Burn, but it only darkens based on the underlying colour values without having an impact on contrast. It has a tendency to turn dark pixels into solid black.

The Darker Colour mode compares the base and top colours and keeps the darkest pixels. No blending is going on here — the lighter colours just vanish. It is ideal for removing white backgrounds. You can create some cool effects with this mode.

Lighten blending modes

Not surprisingly, all these modes will lighten your image. Black is the neutral colour, and any black pixels in the upper layer will disappear, leaving the underlying pixels unchanged. Anything lighter than black has the potential to lighten the layer below.

05 - Lighten Modes

Image 5 — The lighten blending modes

Again, I left out the first mode, Lighten, because the effect is very similar to Screen. All the colours are compared, and Photoshop keeps the lightest ones from both layers.

Screen is the inverse of Multiply. It’s like projecting two slides onto the same spot with two projectors. This blending mode comes in handy when you want to extract shadow detail. You can also simulate a multiple-exposure image by blending a number of slightly underexposed images together.

Colour Dodge lightens your image by decreasing its contrast. Light pixels tend to turn into solid white, but it keeps black pixels. Using this blending mode on a layer filled with 50-per-cent grey, you can give dark hair instant highlights.

Linear Dodge lightens your image by increasing its brightness. In general, this isn’t a blending mode you’ll often use, because it tends to turn all light colours into white. More often than not the image will look unnatural.

Lighter Colour not only lightens, but also increases the saturation. It is the opposite to Darker Colour, and you can get some unexpected results. Photoshop compares the base with the top colours and keeps only the lightest pixels. It doesn’t combine any colours.

Contrast modes

This is a group of seven blending modes. The neutral colour here is 50-per-cent grey. Any pixels lighter than middle grey in the top layer will lighten the underlying image, while any darker areas will darken the bottom image. It’s like a combination of Darken and Lighten modes. The result is an increase in contrast.

I use the Overlay blend a lot in combination with the High Pass filter to enhance local contrast, making the image look sharper. If the effect is too strong, you can always reduce the Opacity setting. Seasoned Photoshop jockeys do all their portrait retouching non-destructively with the Dodge and Burn tools in Overlay or Soft Light mode. Soft Light does almost exactly the same as Overlay, but more subtly.

Hard Light is a combination of Multiply and Screen modes. It is the equivalent of shining a harsh light on your image.

06 - Contrast Modes

Image 6 — The contrast blending modes

In the Vivid Light mode, Photoshop applies Colour Burn to increase the contrast of colours darker than 50-per-cent grey, and Colour Dodge to decrease the contrast of colours lighter than middle grey.

Linear Light is similar to Vivid Light, except that it adjusts the brightness rather than the contrast of the underlying image.

Pin Light is great for producing some special effects in combination with creative filters. It combines the Darken and Lighten blending modes, switching between the two depending on whether the pixels of the upper layer are lighter or darker than middle grey.

With Hard Mix you get a particularly strong result because all the colours are reduced to the six primaries: red, green, blue, cyan, magenta, and yellow (plus black and white).

Comparative blending modes

These should really be called ‘psychedelic’. They can turn your photos into some freaky-looking specimens, which might come in handy for a Halloween card.

The Difference mode compares the pixel values between the two layers. What you see is the difference between the two, but represented as the absolute value (always a positive number). This mode is useful when you want to locate the mid tones of an image. You can also use it to align two layers of the same image (for example, two shots at different exposures).

Exclusion is similar to Difference but with a less dramatic effect. Blending with white inverts the base colour, and blending with black doesn’t do anything.

07 - Comparative Modes

Image 7 — The comparative blending modes

These are also called the ‘HSL’ modes. They break up the colours in the active layer into three parts: Hue (the basic colour), Saturation (colour intensity), and Luminosity (brightness).

The Hue blending mode applies the hue of the active layer to the underlying image, without changing saturation and brightness. Saturation and Luminosity work similarly, only affecting one parameter. The Luminosity blending mode is particularly useful when working with the Unsharp Mask filter when you don’t want to get any colour artefacts.

08 - Colour Blend Modes

Image 8 — The colour-attribute blending modes

The Colour blending mode is a combination of the Hue and Saturation modes. Photoshop keeps the luminance of the underlying layer, and picks up the colour and saturation of the top image. This makes it handy for colourizing greyscale images.

And there is more …

There are other blending modes, for example, the Pass Through mode for layer groups. And the Brush, Pencil, and Shape tools have two additional blending modes, Behind and Clear.

Don’t worry if you haven’t got your head around all the blending modes at this point. The best way of exploring them is to experiment. Start on a single image with an adjustment layer on top. The important points to remember are that Multiply builds up density, Screen makes the image lighter, Overlay increases the contrast, Colour changes the colour balance without affecting luminosity, and Luminosity allows you to sharpen images without the dreaded colour fringes. Don’t forget that you can reduce the strength of the effect by reducing the opacity of the top layer.

Needless to say, the possibilities are only limited by your imagination. In next issue’s article I will show you some practical applications for these techniques in your day-to-day editing work.

Colour adjustments

iStock_000012201422XXXLarge

Hans Weichselbaum walks us through correcting an image with problematic colours

Getting colours right is one of the main challenges in digital imaging. Concerning hardware — cameras, monitors and printers — we have seen huge improvements in recent years. Longevity of inks and fading colours, major challenges just a couple of years ago, are not big issues anymore. But still, we often come across images that don’t seem right, and in many cases it is just a matter of adjusting the colour balance. Perhaps the Auto White Balance of your camera didn’t catch the scene properly, or you have a scan of an old photo with faded colours. You might also try to warm the colours of a portrait shot or reduce the red cast of a scene taken in artificial light.

A few months ago we looked at colour management. This is always the first step, making sure that monitor and printer give you an accurate colour representation of the image pixels. Only when you are working with a calibrated monitor and the right printer profiles does it make sense to fine-tune the colours.

01_ Colour_WheelFirst, we’ll look at the White Balance — that’s where it all starts. Then we’ll go through some of the common tools for tweaking colours, which you can find in every digital imaging program. Finally, I’ll introduce you to two methods that can be quite handy. They allow you to snap an image straight into the optimum colour balance. But let’s start by looking at the theory behind colour adjustment.

The colour wheel

The visible region of light covers the electromagnetic spectrum from 380nm (violet) to 700nm (deep red). If we wrap this around a circle we get the colour wheel (left).

Red, green and blue (RGB) are the primary additive colours, because adding them up gives us white. In-between we find the primary subtractive colours, cyan, magenta and yellow (CMY). These are the colour inks we use for printing and they add up to black. It is important to see the relationship between all of these colours. Once you understand the links, then getting rid of a colour cast becomes much easier. For example, if the image has a blue cast, you cannot simply take blue out. You have to shift the colour balance from blue to the opposite colour, which is yellow. In general, all colour adjustment tools give you three controls that adjust the balance between red-cyan, green-magenta and blue-yellow.

02_White_Balance_LightroomWhite Balance — It all starts in the camera

In most cases the Auto White Balance (Auto WB) setting of your camera will do a good job. If not, the colours need to be corrected later in Photoshop. Auto WB works similarly to the human eye: The lightest object in the scene is set to white, or light grey. For example, in a landscape the clouds will be the lightest objects. They are a good indication of the light temperature, and the lightest part of a cloud should come out white or light grey.

If you shoot in JPEG then it is important to get the WB right. A daylight scene will have a strong blue cast if the camera was set to tungsten light. Such a colour cast is difficult to get rid of later when you work in RGB. If you don’t want to fiddle around with the WB, then it is best to leave the camera in the Auto WB setting.

On the other hand, if you shoot in Raw, the camera settings are not critical and you have total control over the WB setting during Raw conversion. The image on the right shows you the WB setting in Lightroom (Adobe Camera Raw, and all the other Raw converters, give you the same controls).

The Eyedropper on the left works as an auto setting when you use it on a neutral light area of your image, for example, a cloud. Or you might prefer the finer control you get with the two sliders, the top one for the Colour Temperature scale and the second for the Tint.

03_Colour_TemperatureColour Temperature is measured in Kelvin (K), with 0K being the absolute zero temperature (-273.16°C). The tungsten filament in an ordinary light bulb glows at about 2800K, and that’s the colour temperature of a light bulb. The surface temperature of the sun is approximately 5500K and that represents our ‘daylight’ reference number. Light is scattered in the atmosphere, which gives us the blue sky, and this is the reason why the colour temperature keeps going up under overcast conditions.

The image on the left shows you the colour temperature scale from candlelight (below 2000K) going up to very high values under blue sky.

The industrial reference value of D50 is not exactly the same as ‘daylight 5000K’, but it is close enough for us to ignore any differences. It is the standard light temperature for professional light tables and viewing booths. A photo print should always be viewed and judged under a 5000K light source. On the other hand, monitors are calibrated to the D65 standard (6500K).

Note that blue is a ‘hot’ colour, while red is a rather ‘cool’ colour. This is the opposite of our traditional thinking, but it does make sense if you think of heating a piece of metal. It will start by glowing dark red, then go through orange, yellow and white. And if a light bulb blows out, it will give a distinct bluish flash.

Coming back to the White Balance setting in our Raw converter, the Temperature control specifies the colour temperature in Kelvin on an amber-blue scale. Lowering the colour temperature makes the image bluer to compensate for the amber light; raising the colour temperature makes the image more amber, to compensate for the bluer light.

The second slider, the Tint control, lets you fine-tune the colour balance along the green-magenta axis, perpendicular to the Temperature control. Negative values add green, positive ones add magenta.

It takes a while to get your head around these controls, because we are used to three sliders in RGB: red-cyan, green-magenta and blue-yellow. Keep in mind that Lightroom, as well as Adobe Camera Raw, also work with JPEG, TIFF and PSD image files, but in general you will want to use the standard colour adjustment tools for fine-tuning the colours in an image.

The common colour adjustment tools04_Colour_Balance

There are many ways of changing the colour balance. The most common tool is the Colour Balance interface (Image>Adjustments>Colour Balance) shown in the above image.

05_Tone_Curve_LightroomHere you find the three sliders we were talking about earlier for adjusting the balance between the primary colours. The interface allows you to do this separately for shadows, midtones and highlights. For example, to eliminate a blue cast in the shadows you would select Shadows under Tone Balance and shift the Blue slider into negative territory (less blue, more yellow).

You can also use the Levels command for colour adjustment. There is a drop-down menu called Channel with a default setting of RGB. The interface allows you to select an individual channel, e.g. the Red channel. You can then shift the red-cyan balance using the middle slider.

The same goes for the Curves command. Similar to Levels, you can make adjustments to the combined RGB channels or to individual colour channels. In the example shown to the right we have the Blue channel 06_Variationsselected and we get rid of a blue cast by grabbing the curve and pulling it down (reducing blue and enhancing yellow). This is like using the middle slider in the Levels command.

But there is more you can do in Curves, for example, if you have a green cast in the shadows and a magenta cast in the highlights, you simply select the Green channel and make an S-curve (increase magenta in the shadows and reduce it in the highlights, without affecting midtones).

Another handy tool is called Variations (Image>Adjustments>Variations) shown on the left. The beginner, who often doesn’t know which way to adjust, will especially feel comfortable with this interface. It shows you the original photo surrounded by six images with the colour balance shifted towards one of the six primary colours. You simply click on the one that looks best and it will be placed into the middle. Then you can further fine-tune the colours, if necessary.

Two more ways of eliminating colour casts07_Match_Colour

When looking at a photograph you often feel that the colours are not right, but it is not obvious where the problem lies. In that case you might try one of the two following methods.

The first one uses the Match Colour command in Photoshop. This comes with an advanced algorithm to match colours and brightness between two images, but you can also use it on a single image.

08_Average_Blur_Colour_Cast_Removal

Open the image and duplicate the layer by dragging the Background Layer over the New Layer button in the Layer palette (it is always a good idea to work on a duplicate layer). Then open the Match Colour command (Image>Adjustments>Match Colour), shown above:

Click on Neutralise to remove the colour cast. If the effect is too strong, use the Fade slider. Also try the Colour Intensity slider to increase the colour range, if necessary. Stay away from the Luminance slider – there are better ways of optimising the lightness (use Levels or Curves instead). You can also change the opacity of the layer, or even create a Layer Mask to limit the colour changes to isolated areas.

The second method uses the Average Blur filter, which was introduced in Photoshop CS. Again, start by making a duplicate layer, then go to Filter>Blur>Average. You will get a layer with a solid colour, the average colour of your image. This will be the problem colour. To get rid of it, you need to invert this colour (Image> Adjustments> Invert) to apply the opposite to our image. Finally, you change the Blending Mode of the top layer to Colour. If the compensating effect is too strong, you can tone it down by reducing the Layer Opacity, shown right.

These two methods assume a neutral colour balance of your photo. They won’t work if there is a strong imbalance, for example with sunset images, which naturally have a strong orange cast.