The zoom subwindow displays a magnified view of the pixels in a small square around a chosen point. The chosen point may be a reference point of a line or circle, a corner of a rectangle or of an angular sector, a point identified by the cursor in the cut subwindow, or a point selected using the mouse in snoop mode.
The selected point is displayed in the center of the zoom subwindow, surrounded by a white or black border. This highlighted pixel is the focus of the zoom subwindow; its pixel coordinates, intensity, q and d values, and theta and psi values are displayed above the cut and profile subwindow.
(If the chosen point is near the edge of the image, it may appear off center in the zoom subwindow.)
To change the extent of the magnified spot, put the cursor in the magnified spot and use the + or - key on the numeric key pad.
When the right mouse button is held down in the zoom subwindow (magnified spot in the lower right corner), the following menu appears:
The first two options relate to the display of numeric image intensity values in each cell of the zoom subwindow. These values appear in a font whose size matches the cell size as magnification is changed. By default the numeric intensity values are shown if the font size is readable; numeric values are omitted when the font size becomes unreadably small. This maintains a smooth response of the zoom subwindow display to cursor movement in the image. This default can be overridden using the option "I Values On/Off," which is a toggle.
The option "I Values Black/White" toggles the color used for the numeric intensity values, and for highlighting the focus (central cell) in the magnified spot.
The option "New Center of Image" allows the user to specify the center point of the image, when the image is not perfectly centered. First place the highlighted central cell in the zoom subwindow at the location which is to be the new center of image. (For example, adjust the position of a cut circle by dragging the center of the cut circle.) Then select "New Center of Image," hold down the right mouse button and slide the mouse to the right so the submenu with the single entry "Move Center to Zoom Focus" appears. When this submenu entry is highlighted, release the mouse button.
Moving the center automatically changes the center point used for generating angular sectors, and the center point used in performing circular integrations. An angular sector defined before selecting "New Center of Image" "Move Center to Zoom Focus" will be forgotten.
The circle, line, and rectangle are not automatically moved when "Move Center to Zoom Focus" is selected. These may be moved to the new center in a separate operation, using the option "Move to Center" on the main menu in the image subwindow.
N.B.: A new center of image can be placed on any pixel of the image, using the ultra-fine positioning of the zoom subwindow available in "Snoop" mode. This ultra-fine positioning is used subsequently as the true center for circular integrations. However, because the circle, line, and rectangle can only be positioned at pixels in the reduced screen image (see Adjusting Position under "Sections (Cuts)" ), the new center will be taken at the nearest screen image point when the main menu option "Move to Center" is used. In other words, when the center point is chosen by the user, the center of a circular cut could differ from the center for circular integrations by as much as four pixels. To avoid such a discrepancy, eschew ultra-fine positioning of the zoom subwindow, and place the new center of image at coordinates divisible by 4 (for 20 cm plate), or divisible by five (for a 30 cm plate).
The remaining options in the zoom options menu relate to marking selected points on the image.
"Mark Zoom Focus on Image" creates a cross hair mark on the screen image at the point corresponding to the highlighted central cell in the zoom subwindow. The point coordinates and intensity are also entered in a list of marked points.
The list can be viewed by rolling out the submenu from "Mark List."
"Remove last Mark" undoes the previous "Mark Zoom Focus on Image": the mark on the image is erased, and the list entry is grayed out, and will be overwritten by the next "Mark Zoom Focus on Image."
Each mark on the list is assigned a letter of the alphabet, which always appears on the mark list. The menu option "Mark Labels On/Off" is a toggle which controls whether the alphabetic labels appear on the screen image next to their respective cross hair marks.
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