What Temperature is the Auto Value the Camara Selected?

[Marc Hildebrant]

Group,

I have a Canon Rebel xti camara.

When I use the White Balance Auto setting, the Camara selects the White Balance Temperature for me. When I then import the raw camara data for my picture, I can modify the setting by using the Canon DPP4 program. However, I cannot find a way to know what the actual K temperature was selected by the camara for the shot.

I can select various white balance settings and toggle back and forth between "as shot" and my selection to see which one is closest, but that is a poor method.

Where can I find the specific K temp used for an auto setting?

Marc

 

[Marc Hildebrant]

I will answer my question. For a raw image, the white balance is set after the image is created with the auto software. The specific value is not shown as the canon software is proprietary to achieve the correct balance.

Marc

 

[wfooshee]

I can't answer for the Canon software, but when I load a RAW file into Photoshop, I do see the color temperature of the image.
As far as the camera's selected white balance, the RAW file contains that as a metadata setting, and not actually processed into the image yet. The software, be it your Canon software, or Adobe RAW in my case, presents the image to you with that setting, not some automatically-chosen override (I don't think.) It may not tell you what the color temperature is, but it's using the camera's metadata, I'm pretty sure.

 

[480sparky]

A color temp would need to be recorded as it is used to render the .JPG you see on both the camera's screen as well as your computer monitor.

 

[Marc Hildebrant]

With Canon DPP4, meta data/info shows only "auto" for white balance mode, as I said with the original posting...hence my question.

If I change the value to a specific K value, that number will now show in the info view. The specific value canon picked for "auto" is just not shown.

Marc

 

[480sparky]

Will a dedicated EXIF viewer app show it?

 

[wfooshee]

A reason not to use the software, as far as I'm concerned. But as 480sparky said, a downloadable EXIF viewer might show that data from the RAW file.

 

[smoke665]

Group,

I have a Canon Rebel xti camara.

When I use the White Balance Auto setting, the Camara selects the White Balance Temperature for me. When I then import the raw camara data for my picture, I can modify the setting by using the Canon DPP4 program. However, I cannot find a way to know what the actual K temperature was selected by the camara for the shot.

I can select various white balance settings and toggle back and forth between "as shot" and my selection to see which one is closest, but that is a poor method.

Where can I find the specific K temp used for an auto setting?

Marc

Try this link to Canon knowledge base Canon Knowledge Base - EOS Digital Rebel XTi : How to adjust the white balance pretty self explanatory

 

[480sparky]

It appears the OP took a shot with Auto White Balance, but wants to know the specific K that was selected by the camera.

 

[wfooshee]

Yeah, he's not asking how to adjust, he's asking how to see what the camera set as its auto selection.

 

[480sparky]

Raw Therapee will do it.... at least for Nikons.

 

[smoke665]

Apparently no one took the time to open the link. Here's the first instruction.

1 Press the <WB> button. [White balance] will appear. 2 Select the white balance. Press the < > key to select the desired white balance setting, then press the shutter button halfway. The "Approx. ****K" (K: Kelvin) displayed for the selected white balance is the respective color temperature.

Also, the OP said "I can select various white balance settings and toggle back and forth between "as shot" and my selection to see which one is closest, but that is a poor method." the 2nd part of the link gives instructions on setting a custom WB.

As to any WB in a RAW file, it's irrelevant because there is no WB in a RAW file. Any WB information supplied by the camera for "ATUTO WB" or other modes offered by the manufacturer is merely a set of instructions as a line item in a metadata side car. The one chosen as default when you took the shot is what is used to create a JPEG preview. If you edit with a parametric editor then the RAW file is still not altered, but a new set of instructions is generated for WB, that can also be changed. If you use a raster editor only then is the RAW file forever changed.

So far as what's written in the metadata by the camera, there are some paid apps out there that will read the metadata, as well as some free online apps, but again it's irrelevant. Temperture is a function of the light and exposure which can and does change. Depending on the shot and location I might set the WB in post off something in the shot, use a White/Gray/Black target to adjust, or in studio a custom Color Checker profile for the set. Knowing the temperture set by the camera is a useless piece of information, unless you're using the camera WB setting in conjunction with Color Correcting Gels to offset the difference between flash and ambient light. In that case the information provided above is sufficient to determine which camera setting to use.

 

[wfooshee]

It's not irrelevant to the OP. There is a value selected by the camera when it's on Auto-WB, and he wants to know what the camera selected. it's absolutely true that the WB metadata is only used to set the JPG preview, or the default for the image in an editor, but it's still not irrelevant to the OP's curiousity. As for the menu to select WB, of course he can choose a color temperature to use, but that still doesn't tell him anything about what the camera sets as auto.

It's true that it really doesn't matter what the camera set because you can set whatever you need to in post, but the OP might simply be trying to learn something about his camera through the process of seeing how it looks at different situations.

 

[smoke665]

It's not irrelevant to the OP. There is a value selected by the camera when it's on Auto-WB, and he wants to know what the camera selected. it's absolutely true that the WB metadata is only used to set the JPG preview, or the default for the image in an editor, but it's still not irrelevant to the OP's curiousity. As for the menu to select WB, of course he can choose a color temperature to use, but that still doesn't tell him anything about what the camera sets as auto.

It's true that it really doesn't matter what the camera set because you can set whatever you need to in post, but the OP might simply be trying to learn something about his camera through the process of seeing how it looks at different situations.

As the OP never mentions any reason for wanting to know the Auto WB temperature, your assumptions of relevancy are no greater than mine and it's still irrelevant on a RAW file.

All camera manufacturers use a proprietary best guess algorithm to set the Auto WB based on 18% gray within a limited range of about 3000k to 7000k. Additionally each manufacturer has different priorities of accuracy/inaccuracy as to what might be the best guess. When the camera takes the shot, it assigns the WB based on the exposure of the image and the manufacturer's algorithm . Since overexposure/under exposure will affect the Auto WB choice, in post the proper method with a RAW file is to first adjust the exposure....then set the WB. That's one of the advantages of a RAW file, and as said earlier, knowing what the camera did in Auto WB is irrelevant, because post adjustments don't consider any part of the Auto WB.

If you're shooting for SOOC JPEG's then understanding "how" your camera determines WB might be important, because of the differences in the alogrithms (some may give more prefrence to green, or red or blue), but even then knowing the exact temperature it assigned isn't really relevant because the WB is already baked in.

If you absolutely need to know the color temperature of a scene then there are several spectrometers on the market ranging in price from a few hundred dollars to several thousand dollars.

 

[480sparky]

It may also be something as simple as using the value to set the WB in a different camera.