Method for extracting raw data from an image resulting from a camera shot

Method for extracting raw data from a digital image taken by a photographic or cinematographic camera for correcting the extracted raw data and for generating an improved digital image containing the corrected raw data, said method comprising:

• determining, for each point of said image located by column C and line L of the image, a value V0[C, L] consisting of a combination of colour components of the image, expressed as:
• V0[C, L]=α Red [C, L]+β green [C, L]+γ blue [C, L]
• wherein α, β, γ are coefficients satisfying the following relationship
• α+β+γ=1
• α+β+γ≧0
• calculating, for each point of the image, a threshold value VBack.(C, L),
• calculating for each point of the image, raw data consisting in the difference D[C, L] by means of the relations D[C, L]=VBack.−V0[C, L] in the case where the image comprises dark data on a bright background and V0[C, L]−VBack. in the case where the image comprises bright data on a dark background, and
• calculating a threshold value VS consisting of a noise contextual datum from at least one contrast histogram and/or from the probability q that a regional maximum of the raw data contains noise,
• correcting said raw data by using the threshold value VS for:
• either calculating projective deformation and corrections to be made depending on said projective deformations
• and/or by comparing for each point of the image the value D[C, L] with said threshold value VS to determine a corrected raw data value D*[C, L] to be extracted in the following way:
• if D[C, L]<VS then D*[C, L]=0
• if D[C, L]≧VS then D*[C, L]=D[C, L]
• else
• D*[C, L]=D[C, L]−VS
• calculating, for each point of the image, a corrected value I*[C, L] from the corrected raw data D*[C, L] by the following relation
• I*[C, L]=Imax−f.D*[C, L]
• with Imax=value of a bright background or
• I*[C, L]=Imin+f.D*[C, L]
• with Imin=value of a dark background
• storing the corrected value in a memory so as to obtain said improved image.