Blue-violet color shift during compression or color space conversion — common artifact in poor grading or wrong codec choice. Kills DCP quality fast.
If you suddenly notice a bluish-purple cast in color correction that wasn't there before — especially in the midtones or shadows — then you're dealing with the periwinkle effect. This isn't a creative choice, but a technical error that occurs during color space conversion or codec compression. You usually only notice it when the DCP arrives or when you switch back and forth between different working spaces. Suddenly, your clean grade looks like a color cast you never made.
The reason usually lies in the transformation between color space standards — typically: from your linear or sRGB working space to DCI-P3 or vice versa. It gets particularly nasty if you're working with 8-bit instead of 10-bit, or if the codec (h.264, h.265 at aggressive bitrates) compresses the color channels asymmetrically. The blue component is then weighted more heavily, or the chroma is reconstructed incorrectly, and presto — everything looks like it's been pulled through a cold blue filter. You see this primarily in skin tones or in already desaturated areas.
To avoid this in editing: Work consistently with a fixed color space — ideally ACEScc or your project standard — and don't convert back and forth wildly. If you need a deliverable grade before the DCP, do it in a test run and check the export on a calibrated monitor. Some colorists work with LUT previews to catch exactly these kinds of surprises during encoding. Codec choice is critical here: ProRes 422 HQ is more tolerant than h.265 at low bitrates. In professional color pipelines (Resolve, Baselight), it helps to check the dither settings and ensure the bit depth is correct during export.
The name comes from the typical light blue-purple tint that appears — less from a specific botanical reference and more from the descriptive perception. That your image suddenly looks as if someone has laid a periwinkle-colored filter over it. Professionals sometimes also speak of color shift or chroma misregistration, depending on whether it's about the overall color shift or specifically about channel misalignment. With clean workflow discipline and the right LUT tests, this won't happen to you twice.