Camera menu commands

The Camera menu offers the following commands:

Parameters command (Camera menu)

Use this command to open the Camera Setup dialog box and set parameters like exposure time, field of view and binning for the 5 different exposure modes.

Shortcut Key:CTRL+P

Prepare Gain Ref or Acquire Ref in Server command (Camera menu)

When this command is labeled Prepare Gain Ref, it will open the Gain Reference dialog box and acquire a gain reference that will be used for gain normalization within SerialEM.  For DE cameras with a new enough server version, it is labeled Acquire Ref in Server and will open the Direct Electron Server Reference Maker dialog, which lets you make gain or dark references that will be used by the DE server itself.

Gain Ref Policy command (Camera menu)

Use this command to open the Gain Reference Policy dialog box and set options controlling which gain reference is used for gain normalization within SerialEM when several are available.

Search command (Camera menu)

This command acquires an image with the Search camera parameter set, or with the View camera parameters if the option Use View for Search is selected.  In Low Dose mode, images captured with this command are taken with the separately defined Search area microscope parameters.

Shortcut Key:CTRL+E

View command (Camera menu)

This command acquires an image with the View camera parameter set. Either this set or the Search set would be a good parameter set to use for binned, continuous exposures, if continuous exposures work well for the particular camera.

In Low Dose mode, images captured with these parameters are not shifted away from the center of the recording area. The View area is intended to be set up to give a low magnification, low exposure overview. The various procedures which would ordinarily lower the magnification to track positions, such as the eucentricity-finding routines, use View exposures in low dose mode. In other words, these routines rely on the parameter set giving adequate exposures for low-mag tracking in low dose mode.

Shortcut Key:CTRL+V

Focus command (Camera menu)

This command acquires an image with the Focus camera parameter set. This parameter set is used by the Autofocus routine to acquire two or three images in quick succession, so it is typical to set it up for a small image that can be read out quickly, such as the central quarter of the field, with somewhat short exposure and drift settling times. It would be nice if one could also use this parameter set for visually assessing focus, but one usually wants a larger area for that purpose.

In Low Dose mode, images captured with these parameters can be, and typically are, shifted away from the center of the recording area.

Shortcut Key:CTRL+F

Trial command (Camera menu)

This command acquires an image with the Trial camera parameter set. This parameter set is typically set up to acquire a full-frame image relatively quickly. It is used extensively by various routines that do tracking (e.g., eucentricity-finding routines). You should thus make sure that this parameter set gives an adequate exposure for tracking. Many of these routines actually compose a separate parameter set, changing the binning and exposure time if necessary so that binned images of no more than 512 pixels are acquired. However, when the tilt series controller acquires tracking images, it uses the Trial parameters without modification. It is recommended that you set these parameters to bin images binned down to no larger than 512 pixels, and that you acquire a full-frame image unless you have some specific reason not to.

In Low Dose mode, images captured with these parameters can be, and typically are, shifted away from the center of the recording area.

Shortcut Key:CTRL+T

Record command (Camera menu)

This command acquires an image with the Record camera parameter set. This parameter set is intended to be used for final acquisition of images to be saved, and the Tilt Series Controller will rely on it being set up for that purpose. In addition, montaging is done by acquiring images with these parameters.

In Low Dose mode, images taken with these parameters define the center of the recording area and can be considered unshifted.

Shortcut Key:CTRL+R

Preview command (Camera menu)

This command acquires an image with the Preview camera parameter set. This is probably useful only in Low Dose mode, where it acquires an image from the Record area, using the same magnification and beam settings as for Record images. It can be set up to provide a very low exposure image of the Record area.

Shortcut Key:CTRL+L

Montage command (Camera menu)

This command will start the acquisition of a montaged image, with the pieces saved to file. If there is not yet an open image file, you will first enter the Montage Setup dialog box, which allows you to specify the number of frames, magnification, and binning. From there, you enter the File Properties dialog box then the Save As dialog box.

Shortcut Key:CTRL+M

Prescan command (Camera menu)

This command will acquire a binned-down montaged image, which allows a quicker assessment of the area that will be captured in an actual montage. The images are not saved to file. However, montaging needs to be set up first, which does entail defining an output file. If montaging has not been started yet, you will first enter the Montage Setup dialog box, then ensuing dialogs for opening a file.

Preview Prescan command (Camera menu)

This command will acquire a binned-down 3 by 3 montage with Preview parameters in Low Dose Mode.  There is no need to turn on montaging before using this command, and it can be used when a montage is already open.  A temporary file will be created (although not written with images) and removed at the end.

Use Filter Set 2 command (Camera - Correlation Filter submenu)

The Correlation Filter submenu has a set of commands for controlling the filter used when correlating montage overlap zones.  There are two sets of filter parameters available.  Each set has default values, but the defaults can be changed by adding entries for MontageFilterR1R2S1S2 or MontFilterSet2R1R2S1S2 to the SerialEM properties file.  The only difference between the defaults is in the low frequency filtering applied when 'Treat as very sloppy montage' is checked in the Montage Control panel.  Filter Set 1 has a strong low-frequency filter, which has been found to be important when there are strong, high-contrast features like grid bars in the overlaps zone.  However, this amount of low-frequency filtering can be detrimental when aligning low-dose montages without many features beside the regularly spaced holes.  Filter Set 2 eliminates the extra low frequency filter and may work better for such specimens.

Use this command to switch to Filter Set 2 unconditionally.  If you change filters and want to see the effect on alignment of an existing montage, you need to turn on the Redo Corr when Read option so that correlations are recomputed when the montage is read in.

Use Set 2 in Low Dose command (Camera - Correlation Filter submenu)

Use this command to switch to the second set of filter parameters for correlating montage overlap zones only in Low Dose mode.  A low magnification grid map, taken outside of Low Dose mode, would use Filter Set 1, which may work better for montages full of grid bars.

Divide Set 1 by 2 command (Camera - Correlation Filter submenu)

Divide Set 2 by 2 command (Camera - Correlation Filter submenu)

Use these commands to divide all of the parameters of the first or second filter set by 2.  The filter parameters are tuned to work with a moderate amount of noise in the images. When montaging in Low Dose mode, these parameters will work if either the dose or the binning is high enough (typically 4 for 4K camera).  If taking images with an optimal binning for this situation is not feasible or not desired, then the filter parameters can be divided by to achieve an equivalent effect to doubling the binning.  If you change this selection and want to see the effect on alignment of an existing montage, you need to turn on the Redo Corr when Read option so that correlations are recomputed when the montage is read in.

Test Values for Set 1 command (Camera - Correlation Filter submenu)

Test Values for Set 2 command (Camera - Correlation Filter submenu)

Use these commands to try different values of the filter parameters; your settings here will not be retained between sessions.  Parameters are all expressed in cycles per pixel (Nyquist is 0.5).  Entry boxes will come up for each of the four parameters in turn:
   Radius 1: The negative of the frequency at which the low-frequency filter starts to rise from 0 when the 'Treat as very sloppy montage' option is on; all frequencies below this radius will be set to 0.  Only a negative value should be entered.
   Radius 2: The frequency at which high-frequency filtering starts.  This may need to be lower for very noisy data.
   Sigma 1: The sigma for the low-frequency filter, which is an inverted gaussian that rises from 0 to 1.
   Sigma 2: The sigma for the gaussian falloff of the high-frequency filter.  This should generally be changed proportionally if Radius 2 is changed.

If you want to see the effect of new settings on an existing montage, turn on the following option.

Redo Corr when Read command (Camera - Correlation Filter submenu)

If you change any of the filter settings above and want to see how they work with an existing montage, you need to turn on this option so that the program will recompute the correlations with the new parameters when reading in the montage.  Otherwise, it will use the shifts stored in the .mdoc file associated with the image file.  In fact, with this option on, new shifts will be stored in the .mdoc file every time a montage is read in.

Set Params for Grid Map command (Camera - Correlation Filter submenu)

Use this command to control whether the program uses special parameters for a low-magnification montage and the high-frequency filter that it applies.  These parameters are designed to prevent regular hole arrays inside of grid squares from dominating correlations and giving incorrect shifts. 

The primary aspect of these parameters is a very strong high-frequency filter that attenuates the signal from the hole pattern.  The filter cutoff (radius 2) is expressed in reciprocal microns and the original default is 0.25 / um, which corresponds to a 4 um spacing.  The falloff past the cutoff (sigma 2) is fixed at 1/8 of the cutoff.  The low frequency filter rises from 0 with a sigma 1 of 0.01 and starts at a frequency of 0 (radius 1 is 0) even when 'Very sloppy montage' is selected.

The other aspect is that many correlation peaks are evaluated regardless of the setting of 'Evaluate multiple peaks', either 50 instead of the usual 16, or 100 when 'Very sloppy montage' is selected.

Two entry boxes will open: the first is for specifying the minimum size in millimeters that a montage needs to be for the grid map parameters to be applied.  The geometric mean of the montage's sizes in X and Y is compared with this value.  It should be possible to set a value that discriminates between a map of all or most of a grid, and a montage for data from of a very large area.  However, if it turns out that these parameters are bad for other kinds of grid maps (e.g., slot grids), the use of grid map parameters can be prevented by entering 0.

The second entry box asks for the high-frequency cutoff radius in reciprocal microns.

Set Minimum Counts command (Camera menu)

Use this command to set a minimum required number of mean counts for each montage frame. When a frame is taken that falls below this limit, the program stops and gives you three choices: to retake the image and test it again against the limit, to save the image and go on, or to stop the montage. However, if the property ShootFilmIfMontageDark is set to 1, then the program will first take a film picture, which may unstick the lower shutter on a JEOL. Set the minimum counts back to 0 to disable this test.

Stop Acquire command (Camera menu)

This command will stop image acquisition if it is still in some intermediate state, such as raising the screen or acquiring a dark reference. However, once the request for an image has been issued, stopping will have no effect.

Use View for Search command (Camera menu)

Use this command to hide the Search camera parameter set in the Camera Setup dialog box and use the View camera parameters for all Search acquisitions.  In Low Dose mode, Search will still use separate microscope parameters.  Use this option if you do not use Search mode in Low Dose, do not want to keep track of separate View and Search cameras even if you do use Search, or if you are not using Low Dose mode and want fewer radio buttons in the Camera Setup dialog.

No Mont. Map Params command (Camera menu)

Use this command to hide the Mont-map parameter set in the Camera Setup dialog box. This parameter set could be useful when making montage maps, which often involve different exposure time, binning, or other settings from Record acquisitions.  Whether a montage is made with these parameters is controlled by an option in the Montage Setup dialog box. That option will be disabled, and Record parameters will be used by default, if Mont-map parameters are hidden with this command.

Show Gain Ref command (Camera menu))

This command will place the gain reference that was last used to normalize an image into buffer A and roll the contents of A into B, etc., to the extent that buffer rolling is selected. The gain reference consists of real numbers around 1.0 that are multiplied by the image to normalize it.

Show Dark Ref command (Camera menu)

This command will place the last-used dark reference into buffer A and roll the contents of A into B, etc., to the extent that buffer rolling is selected.

Post-actions command (Camera menu)

This command toggles a mode in which various time-consuming actions are initiated immediately after camera exposure ends, at the beginning of the image readout. These actions can be magnification changes, image shift, and stage tilting. Stage tilting is the most noticeable action, because it means that when you stop the Tilt Series Controller, it will often have already gone on to the next tilt. If this behavior is problematic, you can disable it with this command.  For some cameras, the timing is too unpredictable and post-actions are completely disabled.  For Falcon and Direct Electron cameras that are configured so that frames can be aligned in SerialEM, post-actions are allowed only for images with such alignment, to allow them to be done after the summed image is returned from the camera but before the alignment is performed.  This command will be enabled for such a camera, but the post-actions will occur only when aligning frames.

Normalize Here command (Camera menu)

This command toggles the processing (dark subtraction and gain normalization) of images within SerialEM. This setting is initially determined by the global 'GainNormalizeInSerialEM' property or by the 'NormalizeInSerialEM' property for individual cameras. When it is off, processed images are acquired from the camera interface. When it is on, raw images and dark references are acquired from the camera, and the processing is done in SerialEM. In the case of Gatan cameras, the gain reference could come from DigitalMicrograph or from one prepared in SerialEM, depending on which exists.

This command is disabled either because normalized images cannot be obtained from the interface for the current camera, or because normalization is always done by the camera software for the particular camera.  The latter is the case when the normalization by that software is more sophisticated than what can be done in SerialEM, or when it is important to have the camera acquire normalized images to enable other functionality (e.g., for using drift correction with a OneView camera).

For Tietz F216, F416, and XF416 cameras, normalized images can be acquired from the camera by adding a property 'TietzFlatfieldDir' specifying the directory where the TVIPS flatfield images are located.

Divide 16-bit by 2 command (Camera menu)

This command toggles a mode in which all images from a 16-bit camera are divided by 2 right after acquisition, prior to being received by SerialEM. In this mode, a signed integer image with a possible range from -32768 to 32767 will be produced, instead of an unsigned image with a range from 0 to 65535.  Negative numbers in a dark-subtracted or gain-normalized image will thus be preserved instead of truncated at zero. This could be important for low-exposure images if the dark reference can drift downward.  However, using this option does not increase the range of image counts that can be acquired.  When this mode is selected, the options for treatment of 16-bit data in the File Properties dialog box will be disabled because they are no longer relevant. (The image has already been divided by 2 and will not be recognized as an unsigned 16-bit image.)

Set Extra Divisions command (Camera menu)

If this command is enabled for a particular camera, it can be used to set the number of additional divisions by 2 to apply when acquiring images (e.g., an entry of 3 means divide by 8).  The 'Divide 16-bit by 2' option need not be selected.  If it is selected, then the total number of divisions by 2 is the number specified with this command plus 1, and the images will be signed.  If 'Divide 16-bit by 2' is not selected, images will be unsigned even after the divisions specified by this command.  Thus, if available, this command is a better way than 'Divide 16-bit by 2' for dealing with a situation where the camera can produce more than 65,535 counts.  It increases the range of counts, but not the dynamic range, since there are still only 65535 gray levels.  When some division is specified, this menu entry will appear checked,even though it is not a toggle option, so that you can determine whether there is division just by looking at the camera menu.  Currently, this command is available only for OneView, Rio, and Tietz cameras.

Return Float Images command (Camera menu)

If this command is available for a particular camera, it toggles whether floating point images will be produced when acquiring from the camera.  Unlike division by powers of 2, this option allows an essentially unlimited range of counts without any loss of dynamic range.  These images take twice the memory to hold in the program and twice the disk space when saved.  If both float images and division by 2 or more are selected, both will happen.  Currently, this command is available only for OneView, Rio, and Tietz cameras.  (DECTRIS cameras acquire float images exclusively so the option is not available there.)

Interpolate Dark Refs command (Camera menu)

This command toggles whether the program will compute a dark reference for a particular exposure time by interpolating between dark references for two other exposure times, instead of taking a dark reference to match each exposure. When this feature is enabled, interpolation is used if the desired exposure time is between the times for two existing references separated by no more than 0.2 second. If such references do not exist, a new reference is taken either at the desired exposure time or at an interval of 0.2 seconds from a nearby reference; in the latter case interpolation can then be used. The interpolated dark reference will be at least as accurate as a reference taken to match a particular exposure, because interpolation averages over two estimates of the reference. Thus, it is not necessary to take averaged dark references to get good interpolated references, although averaging will improve the estimate further.

When exposure time is being varied automatically during a tilt series, the program activates interpolation if possible. However, this feature is available only when gain normalization is being done in SerialEM.

Set Frame Align Lines command (Camera menu)

This command allows you to control how much detail is printed to the log window after K2/K3 frame alignment done in the SerialEMCCD plugin to DM.  The default is two lines of output: one with the raw and smoothed movement distance implied by the frame shifts; one with selected residual values.  If enough frames are included when fitting the shifts to allow robust fitting, the residuals given are the average of the weighted mean residuals of the fits (an overall figure of merit), the maximum over the fits of the maximum weighted residuals in each fit (reflecting the worse frame alignment result), and the maximum of maximum unweighted residuals(reflecting the occurrence of bad alignments that could be discarded as outliers).  With no robust fitting, it simply shows the overall mean residual and maximum of maximum residuals.

When you select to show one line, it will show the overall mean residual and maximum of maximum residuals, based on weighted values if there is robust fitting, plus the raw distance moved.

When you select to show three lines, it will compute the Fourier ring correlation (FRC) between sums of even and odd frames and report the frequencies values at which it falls below various levels, plus the FRC at half-Nyquist.

No Norm of DS Dose Frac command (Camera menu)

This command can be used to turn off the normalization of the summed image that is returned from a K2/K3 dose fractionation shot taken without gain normalization.

Always Antialias K2/K3 command (Camera menu)

Use this command to control whether anti-aliasing is applied instead of binning for all images returned to SerialEM; namely in counting and linear modes as well as in super-resolution mode for K2, and in linear mode for K3.

Set Timing command (Camera menu)

This command allows you to enter values for the startup delay, minimum drift settling, and extra beam time needed in the dual shuttering mode of operation. The option is enabled by being in Administrator mode.

Set Quality command (Camera menu)

This command allows you to enter a value for the quality level to set when acquiring images in continuous mode from the current Gatan camera.  Enter a number between 1 and 7 (most camaeras will not have that many quality levels), or enter 0 to have no quality value set.

Set Scanning command (Camera menu)

This command was used to enter parameters to control beam movement and focus changes while scanning with a slit beam.

Set Corrections command (Camera menu)

This command allows you to enter a value for the basic corrections to be done when DigitalMicrograph acquires an image. This value may initially be set with the 'BasicCorrections' property, otherwise it is -1, meaning that default corrections will be done. The value should be the sum of 1 for defect correction, 16 for bias correction, and 32 for linearization. 0 will turn off all default corrections. This command is enabled by being in Administrator mode.

Set Drift Interval command (Camera menu)

It is possible for drift to be compensated during an exposure by using a script command to set the drift rate for the next exposure. This command is used to adjust the interval between changes in image shift during the exposure. The default is 100 ms, which may be too short on a JEOL.

Screen Down command (Camera menu)

This command is used to toggle a mode in which the screen is not raised before a camera exposure. This could be useful for looking at the beam during an exposure.

Simulation command (Camera menu)

This command is used to toggle simulation mode, in which fake images are produced within SerialEM rather than acquired from DigitalMicrograph. It should not be needed for simulation if DigitalMicrograph is started with Ctrl and Shift held down to activate the Faux camera.

Debug Mode command (Camera menu)

This command can still be used to toggle debug mode, although it is now equivalent to adding the key letter Z to the debug output set in the Calibration menu and by the DebugOutput property on startup, and this menu item may be eliminated.  The original use of this item was to make the SerialEMCCD plugin chronicle its transactions in the DigitalMicrograph Output window, but it can also be used to turn on debug output in some camera plugins or their server windows, such as Tietz. The camera controller in SerialEM will also output some timing information in the Log Window.

After turning on this mode, you can debug problems with taking a picture from DigitalMicrograph with the following procedure:

Be sure that the Output window is open in DigitalMicrograph.

Try to take an image of the kind that makes an error occur.

Go to the DigitalMicrograph Results window. At the end will be the last script executed. Open a new script window with Ctrl-K. Copy from the Results window, starting at the line
   Object manager =...
after the last
   DMcamera executing script :
up to the line before
   Exit(retval)

Paste this into the script window. Run the script with Ctrl-Enter. It should give an error message with more details about what is bothering it.  If the solution is not obvious, copy down the error message, save the Results window, and send them to David Mastronarde.