Image is really red underwater with red filter

[Ricardo V.]

JamesBon92007
Here is some raw footage (not color corrected - straight out of a GoPro camera).
Most of the shots are with filter. When not, the footnote I added will report accordingly.
We've used artificial light to fill in and help the colors pop when possible. In any case, its for comparison purposes only.
Hope this helps.
Ricardo
PS: Fine tuning and doing color corrections is easier if the original is shot with the right filter.

 

[divinh]

With all the color correction options available in post-production digital editing, can someone explain to me why anyone needs to use a heavy, "light-eating" red filter to capture underwater video?

If you were to examine the red, green and blue histogram of video you shot without a filter, you will see that the histogram for red has a very small dynamic range; that is, values might range from 0 to 50, instead of 0 to 255 for green and blue. The reason for this is the sensor in the camera tries to optimize for 0 to 255. Without the filter, there's more green and blue, so those are used to set the 0 to 255 range.

With a red filter, green and blue are reduced (filtered out) to the sensor so that their ranges match red. Since the sensor basically tries to range for 0 to 255, you end up with red, green and blue filling the 0 to 255 range and giving you more balanced images.

 

[Hoag]

If you were to examine the red, green and blue histogram of video you shot without a filter, you will see that the histogram for red has a very small dynamic range; that is, values might range from 0 to 50, instead of 0 to 255 for green and blue. The reason for this is the sensor in the camera tries to optimize for 0 to 255. Without the filter, there's more green and blue, so those are used to set the 0 to 255 range.

With a red filter, green and blue are reduced (filtered out) to the sensor so that their ranges match red. Since the sensor basically tries to range for 0 to 255, you end up with red, green and blue filling the 0 to 255 range and giving you more balanced images.

Thank you for posting this. I knew how red filters worked, but I have never heard it explained quite this way before. This explanation is brilliant in its simplicity.

 

[bshort4]

Made the same mistake of buying the cheap knock off flip red filter from China for my cheap knock off GoPro camera. The housing that held the filter was a little to small but it did barely fit. Took it to Cozumel and took some pics on the first dive down to about 70 feet and all of them turned out red red red! So I fell back on my old reliable Olympus TG-3 with no housing and no filter--I knew before I used it that the colors would appear washed out but still better than blood red. Didn't want to buy the Backscatter flip filter not knowing if it would fit on my cameras housing and blow $40. So instead I just bought the more orange "dive" Backscatter filter with no housing for $20 and since I already had a frame I knew fit my camera and see if the filter would fit on it. The holes on the filter matched up but it wouldn't slide all the way into the frame by the holes but a small file fixed the problem and now it fits fine. I have yet to use it but will be back in Cozumel at the end of June to try it out again. Also bought a tray and light set up that works with the knock off GO Pro and my TG-3 so hopefully better pics and videos are on the way.

 

[a_lamonta]

Thanks all for the responses. @Ricardo V. WOW!
I'll be buying the backscatter filters. Now I also have an excuse to go back for another 2 weeks, I need to get new shots with the filters once I get them

 

[JamesBon92007]

Thanks all for the responses. @Ricardo V. WOW!
I'll be buying the backscatter filters. Now I also have an excuse to go back for another 2 weeks, I need to get new shots with the filters once I get them

Ah, yes, and I need to go back and re-shoot all of my videos too! Unfortunately I'm booked for December but maybe I can squeeze something in before then.

Thanks Ricardo V. for not only posting the video but for all of the first-hand info too!

 

[JamesBon92007]

JamesBon92007
Here is some raw footage (not color corrected - straight out of a GoPro camera).
Most of the shots are with filter. When not, the footnote I added will report accordingly.
We've used artificial light to fill in and help the colors pop when possible. In any case, its for comparison purposes only.
Hope this helps.
Ricardo
PS: Fine tuning and doing color corrections is easier if the original is shot with the right filter.

By "Red" filter are you referring to the BackScatter "Dive" filter? I've noticed slight differences between various red filters marketed for "blue water."

 

[Ricardo V.]

Yes. I'm referring to Backscatter's line of filters for GoPro cameras in a standard housing.

I've also used Hugyfot's, but that's when the GoPro is in the housing, it's good too, but of course much more of an investment.

Cheers.

 

[Hoag]

I know that it is easy to "spend other people's money", but the difference in price between the "good" filters such as those offered by Backscatter or GoPro and the "cheap" filters like those on eBay or Amazon isn't really that much (especially when viewed in comparison to the cost of a dive trip), wouldn't the extra $50 (or so) be pretty much a "no brainer"?

I would hate to come back from a once in a lifetime trip and find that nothing I had videoed or photographed was usable because I saved a few dollars.

 

[dberry]

At the risk of repeating another response, remember that a red filter does not add red, it only removes some of the blues and greens. The water has already removed a lot of the red at depth, which is why everything looks so blue/green. Depending on the depth, color of the water, etc, different shades and densities of red filters will balance the colors better than others. But the filter will always make the overall photo darker (you're removing some of the light, not adding anything.) If the water is very clear and not too deep, yes, a dark red will remove lots of the blues & greens and leave an excess of red. Use a milder filter.

As @divinh said above, the problem with not using a filter and trying to correct in post-processing is the red dynamic range is compressed and you can't increase it enough to give a realistic balance. Another problem is while diving the human brain is constantly auto-correcting the white balance you perceive, and when you view your photos afterwards the colors don't look the same as you remember.