Canon small sensors cannot capture reds and purples accurately.

OvinceZ said:

Click to expand...

A single-click WB on that little patch of gray (concrete?) in the top right fixed this one.

--
Lee Jay
(see profile for equipment)

Could you explain exactly what you do to get more correct colours by changing the white balance?

I tried several times to get the correct colour with my G6 to no avail. See the samples on my gallery.

http://ovincez.smugmug.com/gallery/1680295

Vince in Oz

I guess sensor makers and software guys have a way to go to get this right. I will try your suggestions. I so dislike having to tweak camera settings, etc. However, if that is required for accuracy then that is what I will do. Thanks for your help.

Vince in Oz

http://ovincez.smugmug.com/

I took the image with a flash hoping it would correct the inaccuracy. It did not. I will use the white balance to see if this corrects the problem next time I take photos. Or do you have to correct colours in Photoshop?

OvinceZ said:

I took the image with a flash hoping it would correct the
inaccuracy. It did not. I will use the white balance to see if this
corrects the problem next time I take photos. Or do you have to
correct colours in Photoshop?

Click to expand...

If you have a gray card, you can do a custom white balance at the scene with that. If your gray card is too small for that, just make sure something neutral is in the scene lit by the same lighting as is hitting the flowers and correct it in PS with a click white balance (center one in levels or, if you use Elements, color cast removal tool).

--
Lee Jay
(see profile for equipment)

OvinceZ wrote:
Are there any digital camera sensors that capture the accurate reds
and purples of flowers?

There are. Here some comparison shots:



Canon ixus 750 (Powershot SD550) - ISO = 100



Panasonic FX01 - ISO=100



Leica R9 + DMR - 2.8/35-70 APO Macro Elmarit - 1/45 f/22.4 ISO=100 - RAW - Silkypix Developer Studio 2.0

At first sight, the Canon picture looks more vivid. Looking at the pictures near the plant, the ixus picture looks unrealistic while the FX01 rendition looks more like the subject. The petals and sepals in the ixus picture have that "plastic" look that is sometimes attributed to the rendition of the human skin in portraits made with Canon cameras.

The dark burgundy color or the flower is rendered by the Canon as pink, the Pansonic FX01 gives a realistic rendition of the subjects color, very similar to the Leica DMR.

What I miss in most comparative test are comments ons color rendition, which is - in my opinion - one of the most imporltant properties of a camera. This is also true for the recent review of the Canon Powershot SD700 IS on dpreview.
--
Peter M.C. Werner
http://www.leicaphoto.net

I followed this tread up to here, and I think that for most (90% maybe) of your pictures, following ljfinger's advice to lower exposure and play with color balance will help a great deal.

In a few cases, enven the most expensive camera will reproduce purple as blue. Let me explain:

There are two different ways your eyes can see purple. The first and most obvious way is that the object you are looking at is scattering or producing the wavelenght range associated with purple. The second way is by mixing red and blue, which actually fools your eye in thinking it is seeing the purple wavelength.

Since your camera only "sees" red green and blue, the red-blue combination is really easy to pick up. This is why a purple wall (purple paint is obtained by mixing red and blue) appears purple on your camera.

In some cases though, a purple flower will get its color by actually scattering more efficiently the purple wavelengths. Since your camera does not have a purple component on its sensor, it gives you the closest match, which is blue. This problem is rare, since pure purple (not red-blue purple) is rare in nature, but it does occure frequently while trying to photograph purple neons, fireworks, and yes, a few flower types, since those can be true purple.

V.

Many flowers have evolved to display patterns mostly in the ultraviolet realm of the light spectrum where bees can see these patterns more clrearly.
Ultraviolet lies on the edge of what the sensor can gather.

So this makes many flowers come overexposed, especially the red and blue channel, hence the shift in color.

This also happens with blue skies. When the blue channel gets cut off by oversaturation, the sky will start to turn cyan instead of lighter blue.
That is because the Proportions of RGB have been changed.

A fix for these case is to underexpose and try to use RAW if possible.

I found that my Fuji F700 which has a wider Dynamic Range than most cameras, can capture more details in flowers.

I might bring some samples compared to the PRO1.

--

Here is a comparison of what we see and what an insect like the bee see.



Now here is a portion of the light spectrum, and as you can see this is a continuom.

At some point in the visible edges of red and violet the sensor stop 'seeing' and that generates the color shift that we can see with problematic subjects such flower petals.



P.S. I have no idea why these jpegs don't show up directly on this page. !?

It makes sense that sensors will have trouble picking up deep purples if they are at the end of the violet colour zone. The strange thing is the Canon cameras pick up purple but not the really deep dark purple or the deep red/purple of roses. What they depict is a weird image of what the eye sees. This is a real problem and I doubt one that playing with settings will correct but I am willing to experiment and report back.

When looking at red roses we clearly see the petals but images tend to diminish them or blur them. Also, I see many white or shiny parts on some flowers such as red and magenta bouganvillia and roses. I have tried polarizers to eliminate this phenomenon but without much success.

Flowers sure test the ability of sensors to capture images of them.

OvinceZ said:

When looking at red roses we clearly see the petals but images tend
to diminish them or blur them.

Click to expand...

You're just overexposing them. Trust me. If you keep your exposures accurate and use an accurate white-balance reference, you'll be way happier with your shots.

--
Lee Jay
(see profile for equipment)

What I explained only affect purple, and only some times. Washed out colors are usually due to overexposed picture (your's certainly look over exposed).

A polarization filter will not be too useful here, since polarization is strongest for specular (direct) reflection at certain angles only. Flower pettals mainly scatter light instead of reflecting it, whitch does not polarize light as much.

V.

I haven't played with exposure settings. Are you suggesting one shoot always at minus 2/3 or just some flowers? I do thank you people for suggestions that will help take more accurate images. Now if I can solve the focus problems in super macro and macro mode I will be quite happy!

ljfinger said:

You're just overexposing them. Trust me. If you keep your
exposures accurate and use an accurate white-balance reference,
you'll be way happier with your shots.

Click to expand...

Not that easy.

The problem is that many flowers have those bright saturated colors that fall out of the camera's gamut.

By underexposing, you are capturing most of the red but you are also squezzing the Green and Blue channels to the point of killing detail in those channels.

For instance a flower might have values of R 1024 G 64 B 64.

When underexposing to bring the the red down to 256, the G and B channel values becomes 4 and 4 or something like that.

Jpegs normaly have 256 levels to play with so even if you can do something for underexposing, there is going to be a hue shift due that the proportion of RGB have been altered to fit into the narrower camera/sRGB space.

That is why RAW will also help here since we can play with 4096 leves per channel for a 12bit camera.

Another workaround is to avoid shooting flowers under very bright sun light.

OvinceZ said:

I haven't played with exposure settings. Are you suggesting one
shoot always at minus 2/3 or just some flowers?

Click to expand...

Just on very saturated objects like flowers.

--
Lee Jay
(see profile for equipment)

Zarathustra said:

ljfinger said:

You're just overexposing them. Trust me. If you keep your
exposures accurate and use an accurate white-balance reference,
you'll be way happier with your shots.

Click to expand...

Not that easy.
The problem is that many flowers have those bright saturated colors
that fall out of the camera's gamut.

Click to expand...

True enough but I didn't say "perfect", I said "way happier". I know these cameras are capable of much better performance on these subjects than the posted samples.

--
Lee Jay
(see profile for equipment)

Someone posted that the Leica might capture reds better than what I have been getting. Can a 1DsII take accurate photos of these flowers?

I have mentioned the deep or bright reds and dark purples but other colours are not that accurate, either. When I looked at the images on the computer screen it was like a new experience. Instead of wondering how they would turn out I would marvel at what was captured and how sharp or otherwise they were. Those reds are very difficult to focus on. I mean, I have spent considerable time trying to get it right but on examining the images was always surprized and usually a bit disappointed. I will have to try manual focus next time.

From what we are reading here it appears that the lads designing the sensors have not tackled and solved this problem yet. I suppose if hardly anyone complains then little will change. I am surprized that reviews don't point out this problem. They mention other things in great detail. When a phenomenon persists across several different cameras then it must be a problem of sensor design and software.

The camera is no where close to what the brain captures via our eyes. I can see those Bouganvillias clearly but the images are not clear or have shiny parts. Where do those come from? Then the colours just are mind-boggling in some images because they are not there in the LCD when I press the shutter. The more images I take the more disappointing it is. I will endeavour to do some of the things to get better results but I doubt I will be able to with the equipment I have.

I recall that I once tried to take a night shot of a neon sign. I tried all the white balance settings and none would capture the colours accurately. In this case it was yellow and red. Not even close. That was a revelation. The flower thing has me stumped because there is way too much creativity happening in the camera that I prefer was not there. The amazing thing about Australia is that in most places flowers bloom every month of the year. I can go to hardware stores that have flower departments and spend an hour there taking images. Then I can come back in a month and there will be different flowers to shoot.

OvinceZ said:

Someone posted that the Leica might capture reds better than what I
have been getting. Can a 1DsII take accurate photos of these
flowers?

Click to expand...

If it's largely a dynamic range problem, as in your examples, then yes. If it's an out-of-gamut problem, the SLRs have the same problem. The SLRs can shoot in RAW and use accurate color profiles to convert so that's an advantage they have.

--
Lee Jay
(see profile for equipment)