This video critically examines the prevalent issue with white balance settings in professional photographic, video, and cinema cameras. The core problem is that most cameras utilize linear Kelvin increments for white balance adjustment, which does not correspond to linear shifts in color perception. This non-linear relationship (governed by Wien's Law) leads to disproportionate color changes: small Kelvin adjustments at lower temperatures result in large color shifts, while large Kelvin changes at higher temperatures yield minimal color differences. The speaker highlights that, paradoxically, cameras correctly implement non-linear adjustments for exposure settings (shutter speed, aperture, ISO) using "stops" that reflect human logarithmic perception of brightness. The video speculates that this discrepancy in white balance handling might stem from a misapplication of film-era color filter principles to digital Kelvin scales. While Canon's cinema cameras offer a more accurate "equal color increment" setting, most of the industry continues to use the flawed linear Kelvin system. The speaker advocates for a universal adoption of equal color increments for white balance adjustments in cameras and software, similar to existing "mired" units, to provide photographers and videographers with more intuitive and effective control.
Summarizing the Flaw in Camera White Balance
0:02 The Problem with White Balance: Professional cameras often perform white balance incorrectly by using equal Kelvin increments, leading to distorted or "off" colors that are difficult to correct.
0:10 White Balance Purpose: White balancing compensates for the overall color cast of lighting to ensure white objects appear white and other colors are accurate.
0:24 Manual Kelvin Adjustments: In professional settings, white balance is manually adjusted using Kelvin values (e.g., 5100K, 5200K, etc.), a practice even found in high-end cinema cameras like ARRI Alexa, Blackmagic Ursa Cine, and Red Raptor.
0:48 Non-Linear Color Shifts: A critical flaw is that equal Kelvin increments do not produce equal color shifts. Visual examples show that small Kelvin changes at lower values result in significant color shifts (e.g., very few blue-tinted images), while large Kelvin changes at higher values result in minimal color shifts (e.g., many yellow-tinted images).
1:27 Practical Difficulties: This non-linearity means that at the lower end of the Kelvin scale, it's easy to make images too yellow or too blue with small adjustments. At the upper end, large changes in Kelvin settings produce only minor color shifts, making it difficult to accurately compensate for lighting.
2:04 The Scientific Reason: This non-linear behavior is rooted in Wien's Law, which describes the non-linear relationship between a glowing object's color and its temperature (a 1/T law).
2:26 Industry-Wide Disregard: Despite this established physics, almost all digital cameras and image processing software treat white balance as if it were linear, even in very expensive cinema cameras.
2:41 Canon's Partial Solution: Canon's cinema cameras are a rare exception, allowing users to switch from equal Kelvin increments to a scale based on equal color increments. However, Canon's photo cameras still use the linear Kelvin system.
2:54 Analogy to Exposure: The video draws a comparison to exposure settings (shutter speed, aperture, ISO), which cameras correctly implement using logarithmic "stops" that reflect our eyes' logarithmic sensitivity to light, ensuring equal perceived brightness changes.
3:41 The Paradoxical Discrepancy: While exposure is handled non-linearly with proportional increments, white balance, also a non-linear scale, is adjusted using linear increments in cameras and software.
3:51 Speculation on Origin: The speaker speculates this might be a legacy from film photography, where physical color filters came in equal color increments, and this concept was perhaps inaccurately translated to digital Kelvin settings by software engineers.
4:56 Existing Correct Units ("Mireds"): Units called "mireds" (micro reciprocal degree Kelvin, or more accurately, inverse megakelvin) already exist to describe white balance in correct equal color increments.
5:11 Proposed Solution: The video suggests keeping Kelvin units for familiarity but using "stops" of equal color increments (e.g., 2260K, 3200K, 5500K, 19600K) instead of linear steps (e.g., 2200K, 2300K).
5:52 Takeaway for Photographers/Videographers: Be more cautious and precise when adjusting white balance at lower Kelvin numbers (e.g., 2700-2800K) as small changes have a significant color impact, unlike at higher Kelvin values.
6:08 Call to Action for Companies: Camera, lighting, and software companies are urged to update their products to use settings with equal increments of color change, emphasizing that it's technically feasible and already done for exposure and by Canon's cinema line.