Quality_Improvement_of_Holographic_Interferogram

3.6.1 Quality Improvement of Holographic Interferogram

From our experiments we obtain digital images of black-and-white photographs character that are computer-recorded in the form of bitmap files.

These computer digital recordings do not usually have the quality required for their further analysis. Mostly it is necessary to modify them by means of either normally accessible quality modification programs or specially created private programs.

Currently available software for modification of images

On the market we can find a wide range of commercially available programs for image quality modification. Programs as Adobe Photo Shop by Adobe, Aldus Photo Styler by comp. Aldus, Corel Draw by Corel, Microsoft Photo Editor by Microsoft, Paint Shop Pro by comp. Brightnessc Software, etc., are well known.

The software mostly involves (Pavelek et al., 2001):

• Routines for work with image files – creation of files, opening of files with various file extensions, file saving with various extensions, printing of images, scanning of images, downloading of the images from a camera or cine-camera etc.
• Basic editing routines – return and repeating of the latest step, deleting, copying and inserting the image parts, displacement of the image parts, change of scale of the image display, etc.
• Routines for modification of image geometry – enlargement of image edges, definition of temporary active external or internal areas namely rectangular, circular or polygonal, change of number of dots per inch in the image, triming of the image, various overlappings and rotations of image, etc.
• Routines for global modifications of image quality – contrast a brightness, creation of a negative, thresholding, change of colours, reduction of the depth of colours or grey shades, conversion of colour images to black-and-white (or vice versa), filters for smoothing or highlighting of graininess in the image, special filters for various other effects in image, routines for required deformations of images, routines for image recreation, routines for histogram, equalisation, etc.
• Routines for local modifications of images – stamping, increase and decrease of intensity, image blurring and various drawing routines (drawing of points, abscissae, rectangles, polygons, stars, circles, curves, filling area of the same colour by another colour, area filling by defined colour up to the boundary, colour replacement in image, spray application, brush or rubber application, writing of texts, adjustment of colours and line-width for drawing, etc.).
• Routines enabling several software adjustments by the user – window design of individual images and control panels, scale display around the image, etc.
• Routines offering various information – about the coordinates and colour on the cursor position, about dimensions of windows or inserted objects, about the image parameters, etc.

Special software for analysis of interferograms

During the analysis of visualisation experiments the work with currently available commercial programs is of low efficiency, as they are not able to process and analyse the image information and present the results in desired form.

The final results of visualisation experiments in the form of tables, graphs, etc. are more suitable to process either by private software or final calculations and graphs by Microsoft Excel, Math Cad, MatLab, etc.

The most favourable is to use our own software for quality modification and analysis of holographic interferograms. Such software, however, must be created in cooperation with skilled programmers who know the algorithms for image quality modification to be applied into our proper program systems.

If we want to create a complex system for the analysis it is necessary to cope also with the designing of applications.

Those are algorithms for either global or local image modifications. The global image modifications are executed by algorithms for modification of image geometry, contrast and brightness, Gauss contrast and brightness, various filtrations of images, image recreation, algorithms for histogram and equalisation, etc. The local image modifications are executed by algorithms to retouch the defects but also by various drawing algorithms. Algorithms for global modifications are referred either to the whole image or its parts temporarily determined by so-called area (window), algorithms for local modification of images are related to the close surrounding of the actual point given for example by the mouse position, whereas it is possible to apply them in any point of the image or only in the temporarily determined area.