Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu SATELLITE IMAGE ARTIFACTS DETECTION BASED ON COMPLEXITY DISTORTION THEORY Avid ROMAN GONZALEZ Mihai DATCU Avid Roman Gonzalez 2011 IEEE International Geoscience and Remote Sensing Symposium 26/07/2011 Vancouver, Canada

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu OUTLINE  The Artifacts, problematic.  Rate-Distortion Function  Kolmogorov Complexity  Kolmogorov’s Structure Function  Experiments and Results  Conclusions Avid Roman Gonzalez

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu ARTIFACTS :  The artifacts are artificial structures that represent a structured perturbation of the signal. Therefore, these artifacts induce errors in the indexation of the images. Avid Roman Gonzalez 3/47

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu AliasingStrips Saturation... Blocking Avid Roman Gonzalez 4/47

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu Data cleaning, or data cleansing or scrubbing - Detecting and removing errors and inconsistencies from data in order to improve the quality of data. Data quality problems are present in single data collections, such as files and databases, e.g.: - Due to misspellings during data entry. - Missing information or other invalid data. Avid Roman Gonzalez 5/47

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu  Is to predict or determine the existence of defects, to model it, and then design a method to detect and correct them. For example we have the lines correction methods presented by [Hyung-Sup Jung 2009].  Specific Artifacts.  Using data compression techniques to implement a method more generic PARAMETER FREE regardless the type or model of artifact. Hyung-Sup Jung, Joong-Sun Won, Myung-Ho Kang, and Yong-Woong Lee, “Detection and Restoration of Defective Lines in the SPOT 4 SWIR Band”, Transaction on Image Processing, 2009.

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu  The Rate-Distortion (RD) Function is given by the minimum value of mutual information between source and receiver under some distortion restrictions.  The RD function shows how much compression (lossy compression) can be used without loss of distortion preset value. Avid Roman Gonzalez 7/47

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu  For the artifacts detection, we propose to use the RD function obtained by compression of the image with different compression factors and examine how an artifact can have a high degree of regularity or irregularity for compression. JPEG Lossy Compression JPEG Lossy Compression Image cf 1 Image cf 2. Image cf n Image cf 1 Image cf 2. Image cf n Decompression +-+- Features Vector (compression errors) Features Vector (compression errors) Classification Image Images with different compression factor (cf) Avid Roman Gonzalez 8/47

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu Kolmogorov Complexity Avid Roman Gonzalez 9/47 String String K(x) is a non calculable function is the length of a shortest program to compute x on a universal Turing machine 15 x (Write 0) Write

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu Kolmogorov’s Structure Function Avid Roman Gonzalez 10/47  An approximation of the RD curve using the Kolmogorov complexity theory could be the Kolmogorov Structure Function (KSF).  The relation between the individual data and its explanation (model) is expressed by Kolmogorov’s structure function.  The original Kolmogorov structure function for a data x is defined by:  Where:S is a contemplated model for x. α is a non-negative integer value bounding the complexity of the contemplated S.

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu Kolmogorov’s Structure Function for Texture Discrimination Avid Roman Gonzalez  To evaluate the behavior of the KSF for different textures, we use de Brodatz images databases. We show the textures used for this experiments.

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu Avid Roman Gonzalez  We can observe that the KSF can discriminate more or less the different structure, the curve KSF has a similar shape for each texture group, but the level is different.

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu Artifacts Detection Using Kolmogorov’s Structure Function Approach Avid Roman Gonzalez  To detect artifacts using Kolmogorov Structure Function (KSF), the first step is to watch the behavior of the KSF curve for images with artifacts and images without artifact.  One aspect to consider is how to generate the candidates for the necessary space S. For this purpose, we have generated the candidates using 2 methods: Candidates generation by JPEG lossy compression and Candidates generation by genetic algorithm.

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu Avid Roman Gonzalez KSF using jpeg lossy compression KSF using genetic algorithm  We can observe that the better discrimination is done when we generate the candidates for the space S using the JPEG lossy compression. Also using JPEG lossy compression the approximation to the Rate-distortion analysis is better.

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu Avid Roman Gonzalez  We use the jpeg lossy compression for generate candidates and to draw the Kolmogorov Structure Function for each patch of a satellite image and try to detect the artifacts. For this experiments we use an image with aliasing introduces manually. Aliasing detection in city environmental using KSF and candidate generation with JPEG lossy compression

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu CONCLUSIONS  The Kolmogorov structure function represents the relationship between an element or data with its model, structure, or explanation.  In this work, we have used the Kolmogorov structure function as a approximation of rate- distortion function using Kolmogorov complexity theory and the complexity-distortion theory, so we can examine the complexity of the images to be analyzed, this complexity would be related to the presence or absence of artifacts. Avid Roman Gonzalez 16/47

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu CONCLUSIONS  The generation of candidates for to calculation the Kolmogorov structure function is an important step, in this work was done experiments using 2 methods, generation of candidates by jpeg lossy compression and candidate generation using genetic algorithms, we obtain better results using lossy jpeg compression. Avid Roman Gonzalez 17/47

Competence Centre on Information Extraction and Image Understanding for Earth Observation Prof. Dr. Mihai Datcu Avid Roman Gonzalez