Tag Archives: exercise

DPP: Part 2 – Digital Image Qualities: Exercise 10 – Colour cast and white balance

Part One – Outdoor Scenes

Part one of this exercise is to create three images of scenes using different white balance settings on the camera. The scenes will be in sunlight, cloud and shade on a sunny day. The white balance settings to be used are; auto, daylight, shade and cloud.

These are presented below with my observations

Sunlit scene

Auto

Auto White Balance

The “coolest” in tone-terms of the images.

Daylight

Daylight White Balance

The most appropriate setting for the scene and I think the most accurate/pleasing too.

Shade

Shade White Balance

The image has taken on a yellow tinge, which is most obvious in the clouds and white areas.

Cloud

Cloud White Balance

The yellow tinge is less obvious here than in the ‘shade’ version. In both cases the images look more like evening sun than the late morning sun they were actually shot in.

Cloudy scene

Auto

Auto White Balance

As before, the “coolest” in tone. As far as I know, there’s no reason that should be the case as a rule.

Daylight

Daylight White Balance

Less of a blue tinge to this version.

Shade

Shade White Balance

There’s not a massive difference to the ‘daylight’ version, previous. Very slightly warmer but not significantly so.

Cloudy

Cloud White Balance

The warmest of the images, but adding a yellow tinge to the scene. I think the ‘shade’ version looks slightly better.

Shade on a sunny day

Auto

Auto White Balance

Again the coolest toned image of the set.

Daylight

Daylight White Balance

Slightly warmer.

Shade

Shade White Balance

A warmer tone again. I think is the one I prefer, as the others looked too cold – which the actual scene didn’t appear to be when I was there.

Cloudy

Cloud White Balance

Slightly warmer than the daylight version, cooler than the shade version – but still a bit too cool in tone for my liking.

Part two – indoor/outdoor scene

The next part of this exercise involved a shot with incandescent lighting against a bluish, dusk, sky. Given tungsten bulbs can’t be bought anymore for modern fittings I’ve gone back to an image from an exercise in my first module, and applied different white balance settings in Lightroom. Even then, I think the bulb simulated tungsten but was actually fluorescent; I do wonder whether the course material needs to be updated given it’s simply not possible to do unless you have a stash of old bulbs! The settings to apply were daylight, tungsten/incandescent and auto.

Daylight

Daylight White Balance

The sky appears to be what I’d expect but the interior is very orange.

Tungsten

Tungsten White Balance

The whole image appears far too blue now, even the sky appears too blue.

Auto

Auto White Balance

Slightly more orange than daylight – which includes the sky too.

Custom

Custom White Balance

In the final version I’ve used the white balance picker in Lightroom to select part of the white wall and then adjusted the colour temperature to reach a compromise I think looks like a good balance between outdoor and indoor light.

Conclusion

It’s clear the programmed settings aren’t able to cope with this combination very well, and manually that’s really possible is a compromise – unless selective adjustment of white balance is available.

This has been an incredibly tedious exercise – as I don’t feel I’ve learnt anything I didn’t know before – and it’s been far to involved for no sense of reward. The other exercise, while very technical, at least delivered some sense of new knowledge so haven’t bored me – that hasn’t been the case here. I think I need to try and make sure my assignment involves something creative – else take a break from course photos to focus on a mini-project “just for fun”, as this course’s technical focus does take the fun out of it all.

DPP: Part 2 – Digital Image Qualities: Exercise 7 – Your tolerance for noise

Leave a reply

This exercise looks at the effect noise has on an image. The requirements were an indoor, daylight scene, with a combination of sharp detail and textureless areas – with some of the textureless area in shadow.

I used my TARDIS against a wall where the windowsill casts a shadow. The camera was set up on a tripod and I shot a series of images at 1-stop intervals along the unexpanded ISO range of my camera. Aperture priority was used to maintain a consistent depth-of-field.

With the images done, the exercise is then to record the results of altering the ISO setting.

ISO 100

The text appears sharp and the texture of the white wall is smooth throughout. There’s a small amount of noise visible when zoomed in on the wall shadow and the light details on the open TARDIS door. IT’s not visible when reproduced at the above “web size”.

ISO 200

At web size there are no clear differences. When zoomed in the noise is more apparent where it was observed before – breaking up the smoothness of the shadow area on the white wall.

ISO 400

Again, there’s not much difference, though the white part on the TARDIS door does have some noise that’s noticeable when zoomed in.

ISO 800

When zoomed in, the inside of the TARDIS has areas of obvious noise, but it’s not affecting the overall image too much. Foreground detail is still clear.

ISO 1600

At web size noise is now slightly visible in the shadow on the white wall. When zoomed in the blue of the TARDIS is dotted with red and purple noise.

ISO 3200

Noise is now apparent in the light areas of the image and is bad across the whole image – when zoomed in. I’d say it’s okay for reproduction at a web size still, but I’d expect the noise to be visible on a print.

ISO 6400

Noise has increased again, though it’s still passable at web size. On close inspection thought it looks like a very bad camera phone image:

ISO 6400 – Close-up

Conclusion

In this particular image, noise hasn’t significantly affected the image when viewed at web sizes. High contrast overall has helped in the areas of detail. However, the noise is clearly evident when zooming in on the image – and at larger print sizes the image would suffer. The exercise has demonstrated how prominent noise can become in dark and shaded areas.

DPP: Part 2 – Digital Image Qualities: Exercise 6 – Highlight clipping

Leave a reply

This image required a scen with a wide range of brightness. I chose a canal lock scene, set against the sky as there’s a reasonable range – from shadows in the lock, to the bright ends of the lock gates. Here’s the scene:

A lock on Rochdale Canal

As the exercise instructs, I set up my camera so the highlight clipping warning just appears. The settings were ISO 100, 1/30s exposure and an aperture of f/16:

“Just” clipping

I then took four additional shots – increasing the exposure by one stop each time.

The next step was to review the images on my computer – comparing the various aspects of the highlight areas:

Completely lost areas of visual information

Between the first and second images there’s a clear loss of detail in the branches of the trees, with them seeming to “blur” into the sky:

Original – Tree Detail

Second Shot – Loss of Tree Detail

By the final image even details in dark areas have more-or-less disappeared:

Fifth shot – complete loss of detail

A visible break in the form of an edge between nearly-white and total white

Even in the first image, this is evident, where the white ladder is set against the light-grey sheds in the background – it merges with a solid block of white, with no clear form to it:

Original – Nearly-white and white edge loss

A colour cast along a fringe bordering the clipped white highlight

A “halo” of colour is actually already evident in the image above on the left-hand-side of the ladder – most obvious where it cosses the black lock gate. However, it’s even more evident in the second image – as shown below:

Second image – Colour fringe on ladder

In later images it disappears, as details become blown-out:

Third image – Colour fringe gone with detail

The colour saturation

The blue sky is reasonable in the first image, but by the second image it’s los saturation and is hard to distinguish from the clouds scattered across it:

Original – sky saturation

Second image – sky saturation

Overall, the image taken without any highlight clipping, at the top of this post, has a far more pleasing tone to the sky.

Using Recovery

The final part of this exercise is to experiment with the “Recovery” tool in my software. This makes use of data from the different colour (RGB) channels to “rebuild” clipped channels – taking advantage of the fact that the different channels don’t always clip at the same time.

I noted with very high levels of recovery white areas seemed to become grey-ish and the whole image seemed duller in tone. On the images with a lot of clipping it would bring out edges, but detail was clearly not available.

I set the Recovery to 45 on the first image, which brought out some background detail without negatively affecting the overall image too much – this was the result:

Recovery applied to the “just” clipping image

DPP: Part 2 – Digital Image Qualities: Exercise 5 – Sensor linear capture

Leave a reply

A camera’s sensor reacts to light in a basic “linear” fashion – the more light, the stronger the response, at the same rate. Our eyes and film however do not – compressing the way they receive light so differences are not as pronounced. This means the eye can cope easily with a range of brightness – while a camera sensor does not. Despite this, when we view images they appear as we would expect them to as the camera carries out processing to bring it closer to what we expect to see.

This exercise simulates the effect of that processing to help understand what happens.

Firstly I’ll create the equivalent of a “linear” capture by applying a gamma correction curve. To start, here is the image as processed originally by camera:

Original

Original image – from camera/Lightroom

and here is the corresponding histogram:

Original histogram

As you can see, there’s a fairly even spread of tones here.

Made ‘Linear’

Here is the image with a ‘gamma correct curve’ applied so it resembles a linear capture – as the camera would create before it processes it:

Linear-ised image

This is the curve applied to achieve this:

Correction Curve

And here is the corresponding histogram:

Adjusted histogram

Now the image shows primarily dark tones – so the majority of the graph is dedicated to detail in the light tones.

Returning to “original”

This is the image with a curve applied – similar to what a camera would apply – to bring it back to a similar appearance to the original out of the camera:

Image returned to resemble original

And here is the curve applied to achieve this:

Camera-like curve

Noise comparison

Here I’ve included a couple of close-ups to compare the noise in the dark regions of the images:

‘Linear’ close-up

Correction curve applied close-up

The close-ups show the effect on noise of applying the correction curve – in the dark image it isn’t that evident, however it is substantially more pronounced once the image is lightened – as the dark areas need greater adjustment and contain less detail.

DPP: Part 1 – Workflow: Assignment 1 – Workflow: Introduction

Leave a reply

The first assignment on the digital photographic practice course requires me to divise a themed assignment on a topic that interests me in a field of photography in which I feel comfortable. I’m opting for still-life, as it tends to be my “go to” option – and I had an idea I wanted to explore, so it’s a good opportunity to do so.

I’m aiming to produce a sequence of images on the birth/hatching of a jelly baby… baby. In part the idea comes from seeing the images of Lars Clausen – and similar – albeit I’m not being as ambitious as his work! I can’t recall how I had my original idea, though, unfortunately.

My expectation is the workflow will be fairly straight-forward, but with a difference-or-two from the first two exercises due to it being a different type of assignment. Mainly I expect to shoot several images for a particular setup for the sequence and review the results in Lightroom and reshoot if I”m not happy or have a different idea for the shot. After that I’d move on to the next image setup for the sequence. I think this is appropriate as re-setting up a shot having moved on would be quite time consuming – versus tweaking after reviewing the shots on my laptop. Setting up a shot again being time consuming might better be read as “I’d be too lazy to do it at all.” It’s the kind of thing that would annoy me – given I’d have already had it set up previously!

The Workflow

This is the workflow I’m aiming to work to:

1. Shoot.
2. Review in-camera and revise.
3. Import in to Lightroom, adding basic keywords on import.
4. Add to a collection set.
5. Perform technical edit.
6. Add shots with promise to a quick collection.
7. Decide whether to reshoot, or proceed on to the next shot. Start both at step 1.
8. Add quick collection shots to a new collection (selects).
9. Once the full sequence is done perform basic processing.
10. Flag preferred shots (first selects).
11. Complete processing on the first selects.
12. Choose the final shots for assignment submission.
13. Backup images to external drive.
14. Delete all but the Selects.

I expect others might sometimes have a workflow where they go back to shooting a particular part of the sequence after reviewing the whole sequence, but I’m thinking I’m likely to have a clear idea of what I want the end result to look like before I start – so hopefully revising each shot of the sequence as I go along will result in a complete set of shots I”m happy with at the end.

The next step

I’ve got some props (mini and normal jelly babies) on order, which should arrive in a day or so. In the meantime, I need to develop my shot ideas more – and I’ll be producing a “planning” learning log posts in future to summarise my ideas.

Go to the next post for this assignment: shot ideas.