The present invention relates to [1] a process for producing a pigment composition, including the step of subjecting a raw material pigment composition containing C.I. Pigment Yellow 74, a specific by-product and water to heat treatment at a temperature of from 160 to 210 C.; and [2] a method of reducing a content of a by-product in a raw material pigment composition containing C.I. Pigment Yellow 74, the specific by-product and water, said method including the step of subjecting the raw material pigment composition to heat treatment at a temperature of from 160 to 210 C.

The present invention addresses the problem of providing: a pigment dispersion liquid with which an optical filter layer having the functions of both a color filter and a near-infrared cut filter can be formed by performing a development step once, and with which a thin filter achieved by using a single-layer configuration instead of a conventional two-layer configuration can be fabricated; and a colored resin composition containing the pigment dispersion liquid. The present invention provides a pigment dispersion liquid containing one or more organic color pigments selected from the group consisting of pigment red, pigment green, pigment blue, pigment yellow, and pigment violet, an infrared absorbing dye having a maximum absorption wavelength in a wavelength range of 750-2000 nm, and an oil-soluble organic solvent or an aqueous medium, and a colored resin composition containing the dispersion liquid.

The present invention relates to [1] a process for producing a pigment composition, including the step of subjecting a raw material pigment composition containing C.I. Pigment Yellow 74, a specific by-product and water to heat treatment at a temperature of from 160 to 210 C.; and [2] a method of reducing a content of a by-product in a raw material pigment composition containing C.I. Pigment Yellow 74, the specific by-product and water, said method including the step of subjecting the raw material pigment composition to heat treatment at a temperature of from 160 to 210 C.

The present invention addresses the problem of providing: a pigment dispersion liquid with which an optical filter layer having the functions of both a color filter and a near-infrared cut filter can be formed by performing a development step once, and with which a thin filter achieved by using a single-layer configuration instead of a conventional two-layer configuration can be fabricated; and a colored resin composition containing the pigment dispersion liquid. The present invention provides a pigment dispersion liquid containing one or more organic color pigments selected from the group consisting of pigment red, pigment green, pigment blue, pigment yellow, and pigment violet, an infrared absorbing dye having a maximum absorption wavelength in a wavelength range of 750-2000 nm, and an oil-soluble organic solvent or an aqueous medium, and a colored resin composition containing the dispersion liquid.