Exposure Blending

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Transcript of Exposure Blending

  • the complete guide from

    camera to process

    exposure blending

    christopher odonnell

  • what is exposure blending?

    how exposure blending works

    5 when & why to auto-bracket

    auto-bracketing overview

    what is raw?

    raw adjustments vs. auto-bracketing

    the versatility of bracketing

    10 how to auto-bracket

    bracketing: step-by-step

    manual bracketing

    finaltipsonbracketing

    14 editing in photoshop

    evaluating the brackets

    preparing to blend

    theblendingworkflow

    brushwork and halos

    26 advanced blending

    whentouserefinedmasks

    ghosting & sensor bloom

    creating the selection

    refiningthemask

    the overlay brush

    sensor bloom & exposure blending

    finaladjustmentstotheblend

    48 introduction to luminosity masks

    creating an alpha channel

    highlight vs. shadow selections

    refiningluminosityselections

    creating the luminosity mask

    transitions with luminosity masks

    finishingtouches

    finalthoughts

    71 about christopher

    72 other ebooks

    73 copyright information

  • what is exposure blending?Exposure blending is one of the most powerful ways to create a stunning

    photograph. As youve probably noticed, it can be difficult to capture an entire

    landscape accurately (especially those with a sky) because your camera sensor

    is limited to one aperture and one shutter speed at a time its not possible to

    have two different settings within the same frame. Youll often note that your

    photos rarely live up to what you actually saw exposure blending is one way

    to overcome the limitations of your camera and photograph a landscape with

    the full tonal range that you see in the field.

    Simply put, in order to have a well-exposed landscape youll need one image

    exposed for the brightest tones in your photo (typically the sky) and another

    for the darkest tones (the ground, usually) when the lighting isnt suitable

    to capture it all in one exposure think of sunsets and how differently the

    natural light level is when you compare the sky to the ground. Once you have

    your two extremes, youll blend them together to make one perfectly exposed

    landscape.

    Exposure blending can also be referred to as HDR blending in the sense that

    were expanding the tonal range, and this method will create a more natural

    looking image than tone-mapping with automated software. With exposure/

    HDR blending, you have much more control over the end result by manually

    choosing exactly where you want to blend your exposures together - and

    at what strength you want the blend to be. Its a method that is entirely

    customizable to your scene, which will produce a more pleasing result.

  • In addition to these two photos on the extreme ends, a middle exposure (one thats been light metered for the

    entire image, finding a middle ground between your fastest and longest exposure) is good to have as well for

    any middle ground elements you need to blend in. At times, the gap between your fast and slow exposure may

    be so great, that you end up skipping the optimal exposure for those elements that fall in between the two. An

    example of this would be the water in the below images. Notice how the image exposed for the ground (left)

    has the water slightly overexposed, and the image meters for the sky (right) has some noticeable shadows. A

    middle exposure was needed to balance this out. For intricate images with vast tonal needs - a scene with many

    shadows and highlights - its not uncommon to have 5 or more photos of the same scene at your disposal.

    The range of your exposures will depend entirely on how bright your highlights are and how dark the shadows

    appear. For example, a cloudy day will have very little difference in exposure, but a golden hour image may have

    5 or more stops to your complete tonal range.

    The two different exposures to the left show how vast the

    differences can be in order to capture the full tonal range of the

    scene. As you can see, the setting sun caused some problems

    in exposure. The image where the foreground is exposed well

    (slower shutter speed) has an extremely overexposed sky, while

    the photo exposed for the sky (faster shutter speed) has the

    foreground in complete shadow. To get a proper exposure, I

    needed to combine these two images (in addition to my base

    exposure for the water) to get the result shown to the right. I

    dont want you to be concerned with the how part just yet

    - we will get to that later on. For now, the take-away point is

    that to get a full tonal range, youll need to combine different

    shutter speeds into one image.

    how exposure blending works

  • 1. when & why to auto-bracket

  • To get three different exposures of the same scene, you dont have to calculate your

    settings and manually input a different shutter speed. Auto-bracketing is a common

    feature with digital SLRs, which allows you to capture one photo exposed normally

    (your base image), and then will automatically expose two more one directly after

    the other - of a slower and faster shutter speed than your base. The difference in

    exposure will depend on your camera and chosen settings, but usually 2 full stops

    is the maximum increase/decrease from your base photo that you can use auto-

    bracketing for.

    This is where the term auto-bracketing comes from since youre bracketing your

    images off automatically by capturing the same scene at different exposures within

    X amount of stops.

    This allows you to capture three sequential images of different exposures without

    having to adjust your settings manually its very handy, and helps to streamline

    your workflow when youre presented with a wide tonal range that one exposure

    can not contain.

    For more intense differences in lighting - as youll often find for sunrises and

    sunsets - youll still have to adjust your settings manually to capture more of a

    range in exposure than two stops (or whatever your cameras auto-bracketing limit

    is). Ill explain how to do this soon, but first I want to show you why you should

    auto-bracket instead of adjusting just one RAW file.

    auto-bracketing overview

  • For brevity, a RAW file is the digital equivalent of a film

    negative before it is printed onto paper - the raw state

    of your image that you cant really use as a photo, but

    all the information you need to create a photo is there. A

    RAW file is just that - you cant upload a RAW file to your

    website or email it to others without special viewing

    software, but you can take that RAW file and turn it into

    a universal image.

    RAW is preferable to JPG in many ways, most notably

    because of image quality. When you take a photo in JPG

    format, it is instantly compressed - and this compression

    will take detail away from your photo, thus limiting your

    processing capabilities.

    With a film negative, you can adjust the exposure by

    exposing the negative onto your paper for longer or

    shorter amounts of time. RAW allows you to do the same

    - at least, for a limited amount of stops. Since youre

    working with the unprocessed digital negative, you

    can recover some blown highlights or blocked shadows

    by adjusting the exposure of your RAW file before

    converting it into a more universal file format for display

    or print, such as JPG or TIFF.

    You can artificially adjust the exposure of a JPG image in

    post process, but this is not a true exposure adjustment

    and will not recover any data for you. In the example

    images, we can see the true benefit of RAW when trying

    to recover these blown highlights. In Figure 1, you can

    see that while the foreground is exposed accurately, the

    sky is noticeably overexposed - a common occurrence.

    Figure 2 shows how much detail is recovered by

    reducing the exposure by two full stops in RAW editing.

    In contrast, Figure 3 displays the same reduction in

    exposure (two stops) for the JPG version. Since the JPG

    file holds no additional data, the exposure is artificially

    reduced simply by adding a layer of black tones - there

    is no recovery of data, and the photo looks noticeably

    worse than the RAW adjustment.

    RAW does have its limitations however - it does not

    give you the power to shoot blindly with no regard to

    exposure, and it is always best to achieve a proper image

    in-camera. A RAW file will typically give you two stops

    of recovery capability - if you adjust the exposure more

    than two stops beyond the original exposure, you most

    likely will not recover any additional data and will start

    to notice the quality to deteriorate.

    what is raw?

  • With RAW being such a versatile format for editing,

    why is there a need to auto-bracket when you can

    simply adjust the exposure in RAW and import all

    those exposures into one file? It would save you the

    time of setting up a tripod, taking three (or more)

    images, as well as saving on disk space I thought

    RAW was supposed to be a magical exposure

    recovery tool?

    Its always best to capture the optimal exposure for

    a scene in-camera simply because youll have more

    data in