CORRECTION FILTERS
For the eye, yellow and colors close to it are the brightest, blue appears much darker, red is of medium brightness. Not so with silver bromide. For me, the blue color is brighter, yellow color - quite dark. Blue color, the strongest effect on the emulsion, gives full blackness, which appears as a dark gray stain on the print.
To increase the sensitivity to different colors, occurring in nature, dyes are added to the emulsion, which increase the sensitivity to warm colors, tj. yellow, red and close. This is how orthochromatic membranes were created (have fallen out of use today) and panchromatic. Orthochromatic films were sensitized primarily to yellow and to a lesser extent to orange, while dimming the blue color, but they were not at all allergic to red and not very sensitive to orange.
Currently commonly used panchromatic films are sensitized to all colors of the visible solar spectrum, but also here the color rendering in the picture does not coincide with this, what our eye sees.
Although these membranes are sensitive to yellow to a large extent, orange and red, however, despite this, these colors are still too dark in relation to blue. Therefore, a filter of gold or similar color is used, to allow the yellow color to pass freely, orange and red was subdued by the effect of blue, allowing better action on the color emulsion, passing through the filter without restriction.
Therefore, using a filter does not add a new color, but only suppresses the action of some, already existing. This is how correction filters work, designed to maintain color balance in the black and white scale of the negative.