Ad
Ad
Ad
Pages: [1]   Bottom of Page
Print
Author Topic: color in sunlight difficulty  (Read 4276 times)
Ortez
Guest
« on: February 23, 2004, 09:50:30 PM »
ReplyReply

Mark,

Look at your EXIF info in those raw files and compare the overcast to the sunlight shots. Try and find the primary difference in the good color and poor color shots. It is either aperture or speed or some combination of the two. Are the exposures uniformly good for all shots in all situations. I assume you are not altering the ISO.

I have found that some cameras have the same sensitivity to exposure time and aperture that transparency film often exhibited, where longer exposures gave richer more saturated colors. From you description, this could well be the case. A little experimentation will tell the tale.

Since you mentioned "artistic judgement", is is possible you are creating an image in your mind that is in fact not real. I know after shooting Fuji Velvia for years and expecting certain color renditions, moving to digital was at first disappointing. The digital images were dead on, but that was not what I had come to expect.
Logged
Dale_Cotton
Sr. Member
****
Offline Offline

Posts: 580


WWW
« Reply #1 on: February 24, 2004, 08:21:07 AM »
ReplyReply

Markj wrote:
Quote
When I shoot on overcast days I get fantastic images. This week with sunlight its all wrong

The white balance function in digital capture is essentially a matter of adjusting the raw RGB values according to the colour temperature of the scene's illumination. As you say, on an overcast day this is no problem. The reason for this is that there is a single illumant: grey sky.

On a sunny day, however, there are two illuminants: the sun itself and the sky. When the sun is low its light is closer to the red end of the spectrum, which is in direct contrast to the blue of the sky. Shadow areas are those areas which are not illuminated by the sun, so any photons we receive from them are either reflected off something sunlit (usually a small percentage) or come directly from the sky (usually the majority).*

If you were to use a colorimeter or a grey card in such a scene you would get one reading in the sunlight and another, very different, reading in the shadows. Even your visual cortex can't handle this: under these conditions you will see that snow actually looks blue-grey in shadows instead of pure grey. If you use the sunlit reading, that will turn the reddish light white while making the shadows even bluer; using the shadow-lit reading will have the opposite effect.

Artificially averaging the readings might produce something close to how the human brain would process the same scene. Just like the white balance of a digital camera, the visual cortex will attempt to rectify any illuminant, which is called white adaptation.**

So what to do? The technician's solution might be to use a colorimeter, then average the readings. But does the brain simplistically average the two extremes, or does it weight according to the percentage of the scene illuminated by each, or something else?

I'm just a poor artsy-fartsy type, so you won't get any brilliant technical solution from me. Instead, I can only suggest you do what I do: make a selection of the shadow areas of the scene in Photoshop, remove as much or as little of the blue cast as you like (or make it bluer!); then optionally invert the selection, then remove as much or as little of the warm cast as you like (or make it warmer).

Ortez wrote:
Quote
Since you mentioned "artistic judgement", is is possible you are creating an image in your mind that is in fact not real.
which is not necessarily a bad thing.

I think we can see from the above that there is precious little about our perception of a scene that is "real". The eye takes in photons then translates their vibratory frequencies into subjective colour experience according to sophisticated image processing techniques that includes white adaptation, edge contrast enhancement, etc. In fact, all colour is false colour. There is nothing intrinsically red about 700 nanometer vibrations or intrinsically violet about 400 nanometer vibrations: this is evolution's gift to us. I strongly feel that to the degree that one, as a photographer, is also an artist, one's task is not simply to create an acceptably realistic simulation of the recorded scene. One needs also to imbue that scene with emotional value. Every color has an emotional charge. A documenter attempts to record what he thinks he saw when he looked at a scene. An artist attempts to convey what he wants you to feel when you look at the scene he presents. For an artist, the question is not whether the colours are "accurate" (whatever that means), but whether they remain believable while performing their primary task of orchestrating emotions.

- - - - -
* There was a scientific paper on this subject that appeared on Outback Photo last year, but I can't find it now.

** This is why a white wall viewed in tungsten light from indoors will look reasonably white, even though tungsten light is orangish; but if you go outside in the evening, then look in through a window at the same wall in the tungsten-lit room, it will look a livid yellow-orange.
Logged
QuaqQuao
Newbie
*
Offline Offline

Posts: 15


« Reply #2 on: March 02, 2004, 04:15:09 PM »
ReplyReply

I'm no expert but as you shot in raw, you should be able to make to tif versions from the raw file. One colorballanced for the shadows and one colorballanced for the parts directly illuminated by the sun. Then use layers and blend the two together in selected areas.
Just a thought.

regards
Logged
Markj
Guest
« Reply #3 on: February 23, 2004, 03:46:14 PM »
ReplyReply

Over the last week I've been shooting on very clear (dry air, no inversion) days with cold north winds. Sometimes clear skys, sometimes some cloud cover. Shooting sunlit landscapes, mid morning or late afternoon (in the UK, so the sun is not v high in the winter). With sunlit scenes my color is coming out very... unpleasant. I can't get what I'm looking for. When I shoot on overcast days I get fantastic images. This week with sunlight its all wrong. It looks like 1940s color postcard color. I'm shooting raw, and trying all sorts of different white balance. Nothing comes close to anything acceptable. I didn't have this problem last summer with my D30. (Now I'm using a 300D, but I doubt the camera is the problem.)

I'm a bit confused as normally I can get anything I want from color, but somehow I'm way off base. Part of the problem might be due to atmospheric effects - the color will be different between foreground and background, but I'm having trouble getting the asthetic parts of my brain to come to terms with this? Anyone else faced a problem like this? What to do? I can't belive I'm going to have to change from using artistic judgement and doing what a grey card tells me.

thanks for any help
markj
Logged
Silva
Guest
« Reply #4 on: February 24, 2004, 06:15:46 AM »
ReplyReply

Landscapes? Digital? No, transparency film is still that deliveres what you are looking for.
Logged
Markj
Guest
« Reply #5 on: February 24, 2004, 01:04:01 PM »
ReplyReply

Thanks for your thoughts folks. Today in Cumrbia we had the lovely dark cloudy sky with hellishly red sunlight breaking through and setting the fells (hill sides) ablaze. This light works great for me! Unfortunately I left my batteries at home doh! But I did get 2 galleries to accept my work :-).

The thing I'm confused about is that I've photographed in this light before and not had this problem. Well, perhaps a) I'm just mistaken and have not seen quite this light before and  I'm aiming a lot higher now so am more critical. I'll post again if I find a way of making an acceptable picture from the photos I took.

markj
Logged
dlashier
Sr. Member
****
Offline Offline

Posts: 518



WWW
« Reply #6 on: March 13, 2004, 02:53:06 PM »
ReplyReply

Quote
It looks like 1940s color postcard color. I'm shooting raw, and trying all sorts of different white balance.
What raw converter are you using? I've noted the "old postcard" look sometimes with Adobe CR conversions.

- DL
Logged

Pages: [1]   Top of Page
Print
Jump to:  

Ad
Ad
Ad