Tag: focus

Image Properties

In order to understand images, we need to be able to talk about them. We need to be able to identify various attributes of images, and identify how they are different from other images.

I call these tools “image properties”, but they sometimes might better be considered as “properties of things in images”. Either way, these are things we can identify about images.

Here’s a list of some common properties that an image (or a thing in an image) may have.

  • Brightness
  • Contrastyness
  • Color
  • Saturation
  • Size
  • Position
  • Sillhouette
  • Focus (out of focus vs. sharp)
  • Motion Blur
  • Implied motion
  • Headroom
  • Facing Direction/Looking Direction
  • Distance from camera
  • Perspective Distortion
  • Framing
  • Completeness

Many of these are self-evident, but let’s break it down.

Brightness

How bright is the object? Is it totally white or black? Over or under exposed? Are it’s edges bright, is it totally bright, and/or does it have highlights?

Contrastyness

How Contrasty (yes that’s a real word) is it? In some ways, this is the opposite of blurriness, as contrastiness and percieved sharpness often go hand in hand.

Does this object take up a little bit of space on the histogram, or do we see a full range of tones from black to white?

Color

What color is it? What is the nature of that color? What does that color say about the object? What does the color pallete of the image say? Are there complimentary, or other such color rules, at play?

Saturation

Saturation refers the percieved color intensity of any color or object. How ‘colorful’ is it, basically? Read more on saturation.

Size

How big is the object compared to other objects? How much space does it take up in the frame?

Position

Where (in the 2D image plane) is the object? Is it on one of the third lines?

Where (in space) is the object? Is it near other objects? Far from them?

Silhouette

What is the outline of the object? Is it a blob, or defined? Does it overlap with other objects in the scene

Focus

Is the object in focus? Is all of the object in focus?

Motion Blur

Does the object have motion blur, or is it on a background that has motion blur?

Implied Motion

Does the object look like it should be moving, like a car with blurry wheels, or a person running.

Headroom

If it does have motion blur or implied motion, does the object have space to move in the image, or is it against the edge of the frame?

Does the object have spacing around it, is it “comfortable” where it is, or does the position feel unnatural, like a person’s face up against the far side of a photo.

Facing Direction/Looking Direction

Is the object “open”, towards the camera, or “closed”, away. Is the object towards the edge of the frame or towards the middle/accross the frame.

If there are eyes, are they looking at camera, behind camera, or to the side? Is the head facing the same direction the eyes are? Is the chest (the collarbone) facing the same direction as the eyes and/or head?

Distance From Camera

How far is the object from the camera? Was the photographer fery far away, or very close? Is the object the closest thing?

Can the photographer get closer? Could they go further away?

Perspective Distortion

Does the size of the object relative to other objects in the scene match with our expectations of reality, or have things become amplified? Are flat objects still flat?

If this object is one of a series of similar objects, like columns on a building, how much different in size is this object than the others?

Framing

Does the object have a natural, unnatural, or implied frame around it.

A natural frame like a window, looking through railing poles, or curved tree branches; where an object would be surrounded in a sight that may be expected “naturally”.

An unnatural frame where something has been constructed, placed, or held up to the camera.

An implied frame where there is no literal frame, just a use of shadows and other compositional elements to ‘surround’ the subject.

Completeness

Is all of the subject visible? Is any part not visible implied in existence, like the top of a head. For the parts not visible, is it uncertain what is out of frame? like just how far down an iceburg goes, or how large a crowd is in an image of a close-up of a few people marching.

If somebody is reacting from something, is that something visible?

If a baseball pitcher throws a ball, do we see the ball, or just the pitcher’s posture?

It’s All Relative

I skipped many of the hypothetical questions because they are all the same:
Is this the most [blank] thing in the image? Is is the brightest? The darkest? The only thing in focus? Is it the closest thing to the camera? The furthest? Does it break a pattern? These questions one can ask themselves about almost everything on this list when considering why an image does or does not work, and what to do about it.

Focal Distance and Depth of Field

Before reading this, please understand  depth of field and the focal distance. Remember, the depth of field is how much near-to-far we have in sharp focus, and the focal distance is literally what we adjust when we adjust the focus. What distance away from the camera that the camera is focusing on, from as-close-as-possible to infinity.

There is an interesting and important relationship between these two properties. Let’s first lay it out on the table:

The closer you are focused, the shallower the depth of field. The further you are focused, the deeper the depth of field.


This can be hard to discover without paying attention to, because the relative size of things shrinks as you get further away (ie: perspective),  Thus, how much depth of field you have in terms of image-impact may not change all that much.

Let’s look at two images taken with the exact same image settings. These images were taken in Sacksville waterfowl park, in Canada.

Deep DOF
Shallow DOF

Both of these images were shot at 100ISO, f/8 aperture, 1/500th shutter speed, on a 40mm prime lens, and only about 2 minutes apart.

Notice the depth of field in both images. In the top, it’s what we call ‘deep focus’. Everything from the foreground to the background is in focus. (Okay, not quite everything, I lose a little bit on the railing very close to the camera). In the second flower photo, notice how the background and other flowers are out of focus.

The only thing that changes was the focal distance. Focal distance affects the depth of field. The further away the lens is focused, the deeper the depth of field. This is how I can take both deep focus and blurry-background images without changing my aperture, my lens width, or any other camera setting.

In the following diagram, the blue range is the depth of field. As we focus further from the camera, the depth of field increases.