A method for examining the interior material of an object (2, 4, 6) from a surface of an object using ultrasound having a frequency of at least 100 kHz, wherein the method comprises the step of transmitting at least a first ultrasound signal by a first ultrasound transmitter of a first number of ultrasound transmitters to the interior material of the object (2,4,6) for forming a first image in order to determine, according to for example the principle of inverse wave field extrapolation, where in the interior material of the object reflections and/or diffractions occur, wherein reflections and/or diffractions of the first ultrasound signal from the interior material of the object are received using a second number of ultrasound receivers (16.i) which are acoustically coupled to the surface of the object at positions which are distributed in at least one dimension of the surface of the object, wherein, with each of the second number of ultrasound receivers (16.i), a receiving signal is generated from the received reflections and/or diffractions of the first ultrasound signal from the interior material of the object, wherein each of the receiving signals generated by one of the ultrasound receivers is processed separately, and wherein the separately processed receiving signals of a plurality of, preferably all, the ultrasound receivers are combined to the first image, wherein the separate processing of each receiving signal comprises: a) converting the receiving signal into a separate dataset in a certain data format wherein the dataset is in the form of a picture; and b) using this separate dataset in forming the first image, wherein the method comprises the further step of transmitting at least a further ultrasound signal by a further ultrasound transmitter of said first number of ultrasound transmitters to the interior material of the object (2, 4, 6) for forming a further image in the same way as the first image, according to the principle of inverse wave field extrapolation, said further ultrasound transmitter being different from the first ultrasound transmitter wherein the first and the further image are combined and the combined image is stored in a memory and wherein a same processing means is used for forming the first image and the further image, wherein the receiving signals generated by the ultrasound receivers are separately processed in parallel, wherein the receiving signals are processed in real time, wherein the data format is chosen such that addition of pictures is facilitated, and wherein the first and the further image are combined by addition; wherein the second number of ultrasound receivers is composed of individual groups of ultrasound receivers, each individual group containing a third number of ultrasound receivers, the second number divided by the third number preferably being an integer, wherein the separate datasets of all the ultrasound receivers of one group of ultrasound receivers are combined to a sub-image, and the receiving signals generated by all the ultrasound receivers of one group being separately processed in parallel, wherein each of the sub-images is temporarily stored in a memory at least until it is further processed, and wherein the number of groups is three or more, and wherein a sub-image is combined with another sub-image to a combined sub-image, said combined sub-image being temporarily stored in a memory at least until it is further processed by combining said combined sub-image with a further sub-image, different from already processed sub-images, and wherein the combination of all sub-images is the first image which first image is at least temporarily stored. a) converting the receiving signal into a separate dataset in a certain data format wherein the dataset is in the form of a picture; and b) using this separate dataset in forming the first image,