Abstract: A method of determining the condition of a metal powder for use in an additive manufacturing process, involving processing an image of the powder to measure a surface property of the powder, such as colour, texture or particle shape. The proportion of powder whose measured surface property falls outside a pre-determined range is determined and can be used to decide whether or not the powder is suitable for re-use. The proportion is determined by identifying individual particles in the image which are identified as statistical outliers amongst all of the particles shown in the image when considering a measured surface property. The relevant proportion may be determined statistically.

Abstract: An image forming apparatus comprising an exposure device for exposing an image bearing member to light in accordance with monochromatic image data provided by color separation of inputted multi-color image data to form an electrostatic latent image; a control device for calculating an exposure amount of each pixel of the monochromatic image data to expose the image bearing member with the calculated exposure amount; wherein the control device includes a monochromatic correcting device for calculating a correction amount in accordance with a pixel value of a pixel around a target pixel of the monochromatic image data to correct an exposure amount of the target pixel on the basis of the calculated amount; wherein the control device includes a multi-color correcting device for providing a coefficient for correction of the exposure amount on the basis of the multi-color image data; wherein the monochromatic correcting device controls the exposure amount using the coefficient and the correction amount provided by