Outline vectorization techniques

In the following, we concentrated on the characteristic features and efficiency data of commercial systems and system components for vectorizing binary Images. The systems were tested during visits to various US and European institutions. Principally one can differentiate between two main vectorization techniques center line and outline representation. 

BIRD-HMQC. The most difficult aspect of implementing the HMQC experiment is the suppression of signals from protons attached to C (the center-band or single quantum coherences) in favor of the protons attached to C (the satellites or double quantum coherences). The use of pulse field gradients (PFG, Section 6-6) is the most effective technique, but relatively few spectrometers are equipped with the hardware required for their generation. Fortunately, there is an effective alternative for the suppression of center bands by means of the BIRD Bilinear Rotation Decoupling) sequence, which is outlined by the vector... 

Most techniques for solving large eigenvalue problems fall under the category of subspace iteration methods, which iteratively solve the eigenvalue problem in a linear vector subspace spanned by only a few vectors. Malmqvist173 provides a concise review of the subspace iteration methods most commonly found in quantum chemistry. Here we will outline some of these methods and note recent advances. 

In order to minimize the second-order energy approximation (T) for fixed Cl coefficients a step-restricted augmented Hessian method as outlined in Section II.B (Eqs (30)-(33)) is used. While in other MCSCF methods this technique is employed to minimize the exact energy, it is used here to minimize an approximate energy functional. The parameter vector x is made up of the... 

An obvious disadvantage of the procedure outlined above is that a relatively large amount of memory is needed. It should also be noted that the method is most advantageous for complete reference functions. For simple reference wavefunctions the matrices Aij, C, etc., become very sparse. This sparsity cannot be exploited fully in a vectorized computer code. It may, therefore, be more efficient to use other techniques in such cases. 

The Information contained In a picture Is represented by broken lines following either the center-lines or the outlines of the drawings. These techniques are commonly referred to as vectorlzatlon techniques as they mainly consist of position vectors of the corner points of polygon lines. 

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