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View Full Version : Is There A Black Stretch Adjustment?



DavidNJ
04-30-2009, 09:28 AM
From what I have seen and others have modified as examples, the blacks seem crushed but still containing detail. Is there a black stretch adjustment?

DavidNJ
04-30-2009, 06:33 PM
a hopeful bump.

Peter J. DeCrescenzo
04-30-2009, 06:36 PM
I believe Hunter was able to adjust his GH1 so blacks are less crushed than the default settings.

DavidNJ
05-01-2009, 07:32 PM
This is a frame from Phillips video with a curve layer applied and the default lighten setting. Isn't there away to do this in the camera?

http://www.dvxuser6.com/uploaded/113/1241231464.jpg

Kholi
05-01-2009, 08:01 PM
I don't know if Philip ever adjusted his camera settings but I can attest to not having to worry about crushed blacks.

The camera has it's own built-in curves that you can gently tune positively or negatively.

LizaWitz
05-01-2009, 08:21 PM
This is a frame from Phillips video with a curve layer applied and the default lighten setting. Isn't there away to do this in the camera?

Yes. The camera supports "film modes" which are collections of settings to adjust the shooting characteristics.

So, we know for sure that Panasonic has attempted to give you the ability to configure such settings in the camera, and from what Kholi's said it covers some sort of custom curves setting or similar. Whether it will let you do exactly what you di there or not I don't think we'll know until we get english cameras and investigate them further.

One of the criticisms of the G1 was that these film modes didn't let you adjust things as far as the reviewers wanted. So, Panasonic may have made a good start but not taken us as far as we want to go--- or maybe they took that criticism to heart and gave us more control.

For all the marketing speak, see here:
http://panasonic.net/avc/lumix/systemcamera/gms/gh1/creative.html

Kholi
05-02-2009, 11:13 AM
The Shadow Correction DOES work in Film Mode. However, it's an automated feature and it deals with contrasty scenes, it doesn't just work outright.

I just figured it out while playing around with the settings. It adjusts according to your shadows and the brightest source of light in your image, so it reduces the contrast according to the entire image.

You've got three levels and it adjusts accordingly.

divide
05-02-2009, 11:17 AM
What do you mean, is shadow correction a local adjustment (thus enhancing dynamic), or is this just an equivalent of the contrast setting ?

Kholi
05-02-2009, 11:23 AM
It's independent of the camera's color profile setting. It's an actual feature called SHADOW CORRECTION.

GregGory
05-02-2009, 04:34 PM
I can attest to not having to worry about crushed blacks.

The camera has it's own built-in curves that you can gently tune positively or negatively.


It's independent of the camera's color profile setting. It's an actual feature called SHADOW CORRECTION.

Phew, you've just saved me from a bunch of grey hairs..

DavidNJ
05-03-2009, 03:35 AM
It would still be nice to see some actual footage with the black stretch fixed in the camera.

DavidNJ
05-03-2009, 04:00 AM
It's independent of the camera's color profile setting. It's an actual feature called SHADOW CORRECTION.


Do you mean Intelligent Exposure Control:http://www.panasonic.net/avc/lumix/systemcamera/gms/gh1/ia.html#no07 ?



The Intelligent Exposure function increases the exposure only in under-exposed areas by detecting the brightness level part-by-part in the picture. If the background includes the sky, which tends to be easily washed out, the camera automatically adjusts the aperture and shutter speed to keep the setting slightly under-exposed to prevent wash-out while brightening the darkened area by increasing the ISO only in that area. If the background of an indoor portrait receives insufficient lighting from a flash and becomes dark, the ISO sensitivity is raised in only the low-lit area to make it brighter without causing graininess in the subject's face.

The setting automatically switches to standard in iA Mode. Also, in P/A/S/M Mode you can adjust the intended effect in three levels high, standard or low. When Intelligent Exposure is turned on, the icon changes from white to yellow.

http://www.panasonic.net/avc/lumix/systemcamera/gms/gh1/img/ia/07_img01.jpghttp://www.panasonic.net/avc/lumix/systemcamera/gms/gh1/img/ia/07_img02.jpghttp://www.panasonic.net/avc/lumix/common/img/spacer.gifhttp://www.panasonic.net/avc/lumix/systemcamera/gms/gh1/img/ia/07_img03.jpghttp://www.panasonic.net/avc/lumix/systemcamera/gms/gh1/img/ia/07_img04.jpg http://www.panasonic.net/avc/lumix/common/img/spacer.gif

http://www.panasonic.net/avc/lumix/common/img/spacer.gif

Peter J. DeCrescenzo
05-06-2009, 04:36 PM
Here's how the GH1's "Film Mode Adjustment" features are described in the user manual (English):

http://www.dvxuser.com/V6/images/attach/jpg.gif
http://www.dvxuser.com/V6/images/attach/jpg.gif
http://www.dvxuser.com/V6/images/attach/jpg.gif

Kholi
05-06-2009, 04:51 PM
Do you mean Intelligent Exposure Control:http://www.panasonic.net/avc/lumix/systemcamera/gms/gh1/ia.html#no07 ?


http://www.panasonic.net/avc/lumix/common/img/spacer.gif

http://www.panasonic.net/avc/lumix/common/img/spacer.gif

That's it. But it reads Shadow Correction on the camera. Weird.

But that's it. Works pretty nicely, actually

divide
05-07-2009, 01:01 AM
That's it. But it reads Shadow Correction on the camera. Weird.

But that's it. Works pretty nicely, actually

So.... It kinda Tone Map (http://en.wikipedia.org/wiki/Tone_mapping) while recording, if asked to ?! That's pretty AWESOME ! Thus the dynamic range can be way higher than 6 stops !
Best surprise from this cam along with AF Tracking and 2x sensor crop option !

Ian-T
05-07-2009, 06:22 AM
Someone tell me if this makes sense or not: ..

But in regards to "Intelligent Exposure" are you saying that the camera, when it takes an image, is somehow taking several different exposure levels of that same image and storing it maybe in the metadata? This helps us get the best possible exposure?
Isn't this sort of like how the Red One works?

LizaWitz
05-07-2009, 09:22 AM
But in regards to "Intelligent Exposure" are you saying that the camera, when it takes an image, is somehow taking several different exposure levels of that same image and storing it maybe in the metadata?

No, what its doing is compensating for the fact that we see brightness exponentially, but sensors measure it linearly.

Each stop is double the amount of light, right? But to us, it looks like just one step "brighter". We percieve 10 equal steps of brightness, but the reality is that each of those steps is doubling the light of the previous step.

Sensors sense light in digital form over a linear scale.

So, what its doing is changing the way the sensor data is interpreted to be more sensitive in some areas and less sensitive in others.

You could call it a tone map, but its not using multiple exposures. Its just reading the sensor as if it were non linear.

For example, if the values range betwee 0 and 10 with 0 being total darkness and 10 being the max amount of light the sensor can read, what it does is when converting this to an image, which, for example, we'll say has a range between 0 and 100... instead of making 1 at the sensor be 10 in the image and 5 at the sensor be 50 in the image and 9 at the sensor be 90 in the image, it may make 1-3 range between 1 and 70 in the image and 4-5 be between 70 an 85 in the image and 6-7 be between 85 and 95 in the image and then the range of 8-10 sensor values would be represented by just the values between 95 and 100 in the image.

EG: its a non-linear mapping to adjust for the fact that our eyes view light on an exponential scale, while the sensor measures it on a linear scale.

This gives more effective dynamic range.

OF course, this is just my assumption about how the feature works in the camera based on what others have said..... but this is how you extend dynamic range without taking multiple exposures.

divide
05-07-2009, 09:38 AM
I think it's more subtle than a simple gamma curve adjustment, "intelligent exposure" seems to adjust exposure locally (different scales at different part of the picture : tone mapping).

DavidNJ
05-07-2009, 10:51 AM
Ok...there doesn't appear to be a black stretch per se. It would adjust the shadow region of the gamma curve.

The iExposure is one of those fancy things your really can't do for yourself. It applies a different gain to photo sites based on their level, presumably before scaling. Sort of a dynamic zone black stretch with three settings. It would appear to be a combination and linked black stretch and knee combined.

The contrast may have a similar affect, however they would also affect the midtones and highlights also.

ROne
06-10-2009, 10:47 PM
You can try flattening the contrast (-2) in the film modes, not much room for adjustment - but will certainly take the edge of the black.