Method of and apparatus for processing an image according to a correction level

Claim 2

An image processing method for processing input video signals (11 R, 11 G, 11 B) based on look-up table data and producing said processed video signals, CHARACTERIZED IN THAT said method comprises the steps of: producing signals (19R, 29G, 29B) each corresponding to a particular frequency vaue of a cumulation histogram which is prepared from a respective one of chroma signals (17R, 17G, 17B) of the input video signals (11 R, 11 G, 11 B), and a signal (31) corresponding to a particular frequency value of a cumulation histogram which is prepared from a luminance signal (27) of said input video signals; comparing said signals (29R, 29G, 29B, 31) corresponding to said respective particular frequency values by an arithmetic operation to determine a degree of color correction level; producing adjusted signals by adjusting color correction level of the input video signals in response to said degree of color correction level determined; setting a highlight and a shadow point based on a respective one of said adjusted signals; preparing look-up table data (41 R, 41 G, 41 B) each corresponding to a respective one of the input video signals on the basis of said highlight and shadow points set; and ° processing an image by using said look-up table data (41 R, 41 G, 41 B). 9

Claim 3

A method in accordance with claim 1, CHARACTERIZED IN THAT said method is used with an image recording method which reproduces a visible image in an image recording medium (30).

Claim 4

A method in accordance with claim 2, CHARACTERIZED IN THAT the step of processing an image by using the look-up table data comprises a step of producing density signals (19R, 19G, 19B) by, based on said look-up table data, converting the input video signals (17R, 17G, 17B) into signals (19R, 19G, 19BO each being representative of intensity of light to be projected onto the image recording medium (30) and applying tone correction in matching relation to particular photographing conditions associated with said input video signals (17R, 17G, 17B).

Claim 5

A method in accordance with claim 3, CHARACTERIZED IN THAT the step of setting a highlight and a shadow point comprises a step of preparing cumulation histograms from the invidual adjusted signals (35R, 35G, 35B) and setting a highlight and a shadow point based on a respective one of said cumulation histograms.

Claim 6

A method in accordance with claim 4, CHARACTERIZED IN THAT the degree of color correction level is determined on the basis of a value nf A ,I which is expressed as: where histo(R) h | , histo(G) h | and histo(B) h | are the cumulation histograms prepared from the individual chroma signals (17R, 17G, 17B), and histo-(Y)d is the cumulation histogram prepared from the luminance signal (27).

Claim 7

A method in accordance with claim 5, CHARACTERIZED IN THAT the step of correcting color collection level comprises a step of replacing the chroma signals C (17R, 17G, 17B) of the individual input video signals with chroma signals C' each corresponding to a respective one of said chroma signals C, taking account of the luminance signal Y (27) of said input video signals and by usinq an equation: the value of k being changed in response to an output which is representative of the degree of color correction, whereby the degree of color correction level adjustment is controlled.

Claim 8

A method in accordance with claim 5, CHARACTERIZED IN THAT the step of adjusting color correction level comprises a step of, when the degree of color correction level is determined to be high correction, delivering the chroma signals (17R, 17G, 17B) of the individual input video signals directly and, when, the degree of color correction level is determined to be low correction, delivering the luminance signal (27) of the input video signals directly.

Claim 9

An image processing apparatus comprising: image processing means (14R, 14G, 14B) for processing input videos signals (11 R, 11 G, 11 B) based on look-up table data and delivering said processed video signals; highlight and shadow point setting means (42R, 42G, 42B) for setting a highlight and a shadow point of a respective one of said input video signals (11R, 11 G, 11 B); and look-up table data preparing means for preparing look-up table data each corresponding to a respective one of the input video signals (11 R, 11 G, 11 B) on the basis of the highlight and shadow points which are set up by said highlight and shadow point setting means (42R, 42G, 42B), said look-up table data being fed to the image processing means (14R, 14B, 14G); CHARACTERIZED BY said apparatus further comprising: chroma signal cumulation histogram preparing means (34R, 34G, 34B) each for preparing a cumulation histogram from a respective one of chroma signals (17R, 17G, 17B) of the input video signals; a luminance signal cumulation histogram preparing means (36) for preparing a cumulation histogram from a luminanced signal (27) of the input video signals; a color correction level degree determining means (38) for determining a degree of color correction level by comparing, by an arithmetic operation, signals each corresponding to a particular frequency value of the cumulation histogram of a respective one of the chroma signals (17R, 17G, 17B) which are prepared by the chroma signal cumulation histogram preparing means (34R, 34G, 34B), and a signal corresponding to a particular frequency of the cumulation histogram of the luminance signal (27) prepared by the luminance signal cumulation histogram preparing means (36); and a color correction level adjusting means (40) for producing adjusted signals (35R, 35G, 35B) by adjusting color correction level of the input video signals (17R, 17G, 17B) in response to an output of said degree of color correction level determining means (38); the highlight and shadow point setting means (42R, 42G, 42R) setting a highlight and a shadow point of a respective one of said adjusted signals (35R, 35G, 35B) which are output by said color correction level adjusting means (40).

Claim 10

An image processing apparatus comprising: image processing means (14R, 14G, 14B) for processing input videos signals (11 R, 11 G, 11 B) based on look-up table data and delivering said processed video signals; highlight and shadow point setting means (42R, 42G, 42B) for setting a highlight and a shadow point of a respective one of said input video signals (11R, 11 G, 11 B); and look-up table data preparing means for preparing look-up table data each corresponding to a respective one of the input video signals (11 R, 11 G, 11 B) on the basis of the highlight and shadow points which are set up by said highlight and shadow point setting means (42R, 42G, 42B), said look-up table data being fed to the image processing means (14R, 14B, 14G); CHARACTERIZED BY said apparatus further comprising: chroma signal cumulation histogram preparing means (34R, 34G, 34B) each for preparing a cumulation histogram from a respective one of chroma signals (17R, 17G, 17B) of the input video signals; a luminance signal cumulation histogram preparing means (36) for preparing a cumulation histogram from a luminanced signal (27) of the input video signals; a color correction level degree determining means (38) for determining a degree of color correction level by comparing, by an arithmetic operation, signals each corresponding to a particular frequency value of the cumulation histogram of a respective one of the chroma signals (17R, 17G, 17B) which are prepared by the chroma signal cumulation histogram preparing means (34R, 34G, 34B), and a signal corresponding to a particular frequency of the cumulation histogram of the luminance signal (27) prepared by the luminance signal cumulation histogram preparing means (36); and a color correction level adjusting means (40) for producing adjusted signals (35R, 35G, 35B) by adjusting color correction level of the input video signals (17R, 17G, 17B) in response to an output of said degree of color correction level determining means (38); the highlight and shadow point setting means (42R, 42G, 42R) setting a highlight and a shadow point of a respective one of said adjusted signals (35R, 35G, 35B) which are output by said color correction level adjusting means (40).

Claim 11

An apparatus in accordance with claim 8, CHARACTERIZED IN THAT the image processing means (14R, 14G, 14B) are installed in an image recording apparatus for reproducing a visible image in an image recording medium (30).

Claim 12

An apparatus in accordance with claim 9, CHARACTERIZED IN THAT the image processing means (14R, 14G, 14B) comprise tone correcting means (14R, 14G, 14B) in which the look-up table data are stored, said tone correcting means (14R, 14G, 14B) producing density signals (19R, 19G, 19B) by converting each of the input video signals (11 R, 11 G, 118) into a signal which is representative of intensity of light to be projected onto the image recording medium (30) and applying tone correction in matching relation to particular photographing conditions associated with said input video signals (11 R, 11G, 11 B).

Claim 13

An apparatus in accordance with claim 10, CHARACTERIZED IN THAT the highlight and shadow point setting means (42R, 42G, 42B) prepare cumulation histograms from the individual adjusted signals (35R, 35G, 35B) and, based on said cumulation histograms, sets up the highlight and shadow points.

Claim 14

An apparatus in accordance with claim 11, CHARACTERIZED IN THAT the color correction level degree determining means (38) determines the degree of color correction level based on a value of A which is exoressed as: wherein histo(R) h | , histo(G) h | and histo(B) h | are the cumulation histograms of the individual chroma signals prepared by the chroma signal cumulation histogram preparing means (34R, 34G, 34B), and histo(Y) h | is the cumulation histogram of the luminance signal prepared by the luminance signal cumulation histogram preparing means (36).

Claim 15

An apparatus in accordance with claim 12, CHARACTERIZED IN THAT the color correction level adjusting means (40) adjusts color correction level of replacing each of the chroma signals C (17R, 17G, 17B) of the input video signals with a chroma signal C' (35R, 35G, 35B), taking account of the luminance signal Y (27) of said input video signals and by using an equation: C' = kC + (1 - k)Y the color correction level adjusting means (40) controlling the degree of color correction level by changing the value of k in response to an output (33) of the color correction level degree determining means (38) which is representative of a degree of color correction level.

Claim 16

An apparatus in accordance with claim 12, CHARACTERIZED IN THAT the color correction level adjusting means (40), when the degree of color correction level determining means (38) determines that the degree of color correction level is high correction, produces the chroma signals (17R, 17G, 17B) of the input video signals directly and, when said degree of color correction level determining means (38) determines that the degree of color correction level is low correction, produces the luminance signal (27 directly.