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J Rogowska

Publications and source records attributed to J Rogowska.

5 recordsLinked to original sources
PubMed1989

Evaluation of algorithms for ratio imaging in fluorescence microscopy.

Ratio imaging in fluorescence microscopy is used in measuring parameters such as pH, pCa, cytoplasmic porosity, and the relative concentration of fluorescent analogs within single cells. The fastest method for ratio imaging is to use lookup tables on special-purpose image processors. Since lookup tables store integers in integer addresses, using a lookup table will generate rounding errors. The magnitude of the error will depend on the transformation performed and on the number of levels used in the lookup table. We examined ratio imaging by lookup table and computed the errors generated by both inversion and log subtraction methods. Both uniformly fluorescing fields and fluorescing cell images were employed to provide data for use in confirming our calculations and illustrating both the magnitude and spatial incidence of errors. It is shown that, through proper design of lookup tables, a significant reduction can be made in the errors generated in comparison with common methods available in most image processors.

Algorithms↗
PubMedDate not supplied

Temporal correlation images derived from sequential MR scans.

In this paper a new technique is presented for measuring the local temporal changes and correlation between them on spatially aligned image sequences. A temporal correlation image is derived from a sequence of static images (frames). The method is illustrated in an application to the dynamic MRI of the rabbit kidney following bolus injection of Gd-DTPA. The similarity maps clearly separate the dynamic response of the cortex to the indicator from that of the medulla and, therefore, segment the kidney into two regions. Regions with different temporal dynamics can be displayed in different colors using a lookup table designed for that purpose.

Animals↗