Two Questions: 1) White Balance 2) Compression

[Billy]

1) White Balance question. Shot this image (below) in RAW format. White Balance setting on camera was probably on auto, but it didn't matter as I'd adjust as necessary in PSE 7. I'm wondering what happens when, as in this case, the camera is in the shade, about a third of the photo is in the shade, and about 2/3 of the image is in "daylight". Maybe this shot isn't the best example, as the shady parts are really blacked out. But there are other shots of mine from this trip where half the photo is in shade, but still visible. In PSE7 I can use the slider, so I have total freedom there. But if I didn't shoot RAW and had to set the WB in-camera (assume no photo editing), what do you choose for this type of mixed (shade/sunny) shot? I'm guessing the WB choice is based on that portion of the photo you feel carries the most weight. No, I don't carry a 18% grey card with me.

2) Compression question. The RAW shot is about 12Meg. When I save it in PSE7 as a .PSD file, it's about 46Meg. When I save it in PSE7 as a .JPG file, it's about 5Meg. I understand the .JPG compression, but what happens in the .PSD file to make the file size grow almost 4x? I didn't create any layers (it has background layer only).

 

[MichaelJ]

My guess would be that your raw data is probably 12-bit in a packed format while the .PSD is 16-bit and just a more verbose file format.

 

[DougPaul]

1) White Balance question. Shot this image (below) in RAW format. White Balance setting on camera was probably on auto, but it didn't matter as I'd adjust as necessary in PSE 7. I'm wondering what happens when, as in this case, the camera is in the shade, about a third of the photo is in the shade, and about 2/3 of the image is in "daylight". Maybe this shot isn't the best example, as the shady parts are really blacked out. But there are other shots of mine from this trip where half the photo is in shade, but still visible. In PSE7 I can use the slider, so I have total freedom there. But if I didn't shoot RAW and had to set the WB in-camera (assume no photo editing), what do you choose for this type of mixed (shade/sunny) shot? I'm guessing the WB choice is based on that portion of the photo you feel carries the most weight. No, I don't carry a 18% grey card with me.

The camera applies a single white balance to the entire picture. In cases where there are sections with different lighting, no single balance can do the best job--different white balances need to be applied to each section for the best balance overall.

If there is a known white spot (eg a snow patch), you can get the white balance from that. BTW, the grey card will enable you to get the balance at the camera, but this may not be the same as the balance for the scene. (Also, the lighting at the camera location is irrelevant--only the lighting on the scene is relevant--the grey card is only useful if its lighting is the same as that of the scene.)

In this particular image, the shadow zone is so dark that a single balance for the lit area should be good enough. (There is a small amount of detail in the shadow zone that is visible if you crank the gamma way up. This will probably be better if done from the RAW image rather than a JPEG.)

2) Compression question. The RAW shot is about 12Meg. When I save it in PSE7 as a .PSD file, it's about 46Meg. When I save it in PSE7 as a .JPG file, it's about 5Meg. I understand the .JPG compression, but what happens in the .PSD file to make the file size grow almost 4x? I didn't create any layers (it has background layer only).

I don't know the details of a .PSD file, but the RAW file could be a lossless compressed format. The .PSD file could be an uncompressed format, could have larger data fields, and/or could have more layers.

You don't tell us the camera model so we can only guess about the RAW format. (It's not in the EXIF of the linked image.)

Grand Canyon from Mather Point?

Doug

 

[Billy]

Thanks guys. Here's more data and some replies to your replies. Camera is Canon Rebel XT. When I open the RAW file in PSE7 (well, actually the first stop is the RAW file reader prior to the image opening in PSE7 itself) the bit depth drop-down menu lets you choose 8 bit or 16 bit. I chose 16 bit. At that point a few things happen. You can't crop or straighten the pic....it can only do that in 8 bit mode. When you save the 16 bit file as a .PSD file it's about 46MegaBytes. You cannot save it as a JPEG, the nearest choice is a JPEG2000 file. When I put that JPEG2000 file in my smugmug gallery, you can't see the detailed image data (date taken, exposure mode, f-stop, ISO, etc). Probably some other stuff i'm forgetting.

Now back to opening the pic in PSE7....if I choose 8 bit depth, when I save it as a .PSD file, the file is about 20Meg. And now I CAN save the file as a JPEG. When I put this JPEG file in smugmug, all the image data is able to be seen (below is same pic as in original post, but as a JPEG here, and without crop)

Good guess, but not Mather Point. About a mile down the Bright Angel trail.