Sunday, 23 January 2011

Exercise 22: Addition

The aim of this task is to add an element from a different image using different techniques. The remit to to take a landscape view with a significant area of sky containing cloud detail. Using a tripod take two separate images, one with correct exposure for the sky and the other with correct exposure for the foreground. The images should be processed with minimal compensation and combined using layers if available.

Two different methods for the combination should be used, one using an erase method, the other using a selection tool.

The second part of this project is to import the sky from one photograph to another. The aim being to create a realistic effect. Obvious things to take into consideration will be direction of the sunlight and overall brightness and contrast.

Are these techniques a step too far? How much should you "doctor" an image and why? Is it ethical?

Completion of this task has been delayed mainly due to the poor weather. It has not played ball with me at all, rain, rain and a bit more rain. If not rain complete grey blanket cloud with no real detail and such 'flat' landscapes obtaining working images has been very difficult. Giving up in despair I rummaged through some of my archived shots. Because of this I have not been able to shoot using a tripod, deliberately taking two images correctly exposed for the sky/foreground, but I am familiar with and have used this technique previously. Instead I have chosen an image taken on a cloudy day and altered the exposure in RAW to provide the correct exposure for the sky/foreground.

Altering the Sky - Erasing

A local lavender farm opens it's fields shortly prior to harvesting the flowers. The original image was taken on a cloudy day with intermitent sunlight with the exposure chosen for the foreground. ISO 200 f10 18mm 1/125.

Original Image

Due to the recent inclement weather I have been unable to take images for this task so altered the original image in RAW to correctly expose the sky, bringing out the detail in the clouds and providing the second tiff image to be able to complete this exercise. There was no highlight clipping and the foreground is under-exposed. Had this image been shot to deliberately underexpose, it probably would have had a difference in the region of 2 fstops from the original. My intention is to take some images once the weather inmproves to see how many fstops I do need to alter my images to get this effect.

Altered in RAW to provide Second image

The lighter image was then dragged onto the darker image and the over-exposed sky was erased using a layer mask. I find this method of erasing offers much more control than simply using the erase tool.

Layers with Layer Mask Adjustment

Final Image
Although using layer masks is a better option than the erase tool I still found the area around the tree awkward to correct as I kept getting a halo effect. after some trial and error I obtained a result I was happier with.

Altering the Sky - Selection

The same two images were opened in photoshop, the lighter image placed on top of the darker but instead of using the erase tool the lighter sky was selected and deleted. Quick Mask mode was used to complete the selection with a feathered brush to assist with the blending of the different layers.

Quick Mask Selection

Final Selection Image
Using the selection technique was quicker and provided a more pleasing result, although I don't know if the jpegs on here show the subtle differences. The feathering of the selection was easier to obtain and this meant the sky blended into the foreground with more success first time on deletion.

Reflecting on the process of combining 2 copies of the same image, or shooting 2 frames at different exposures I can see nothing wrong with applying this manipulation technique. In post production we are only compensating for the camera's limited dynamic range. Our eyes automatically adjust to the ambient light and correcting exposure, unless done to the extreme, should have little impact on the content or meaning of the image taken. I have used this technique before and will no doubt continue to do so. To my mind the integrity of the photograph has not been affected, this is the scene as I saw it and it presents a true reflection of that place at that time.

Adding A New Sky

For this second part of the project I opted for an image of a statue taken outside the large greenhouse at Kew. It was a bright but overcast day with very little cloud detail. To get correct exposure for the statue the sky itself was very overexposed so what little detail there was lost and hard to recover.

To prove a point about needing the correct replacement sky I first experimented with a very bright blue sky but although the 'faux' background looked  fairly reasonable behind the statue it looked fake against the greenhouse which did not reflect the replacement.

Experimental test sky

Due to not liking the effect of the bright sky I did not take that much care while adjusting the edges along the trees and greenhouse but it shows that care care needs to be taken with choosing the second image which will provide the replacement background. Brightness, contrast and the direction of light all play a very important part of the decision making.

Experimental Selection

Having used images from the lavender field in the first part of this task I thought this image would be a better option.

Image to provide replacement sky

Both images were opened in photoshop and the selection of the sky from the target image was made using the magic wand tool. The selection was modified by expanding and feathering the selection, this was then tidied up by switching to quick mask mode.  Moving to the cloudscape window I did the following :

Select > All
Edit > Copy

With the cloudscape now held in the memory I returned to the target image. Ensuring the target image still had the sky selected I pasted the cloudscape across Edit > Paste into

The cloud area was then resized using Edit > Transform > Scale

Although the brightness of the sky is more suitable it still is not quite right due to the difference in the depth of field therefore I used the gaussian blur filter to correct this.

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