=====Bad/Hot pixel map===== The bad pixel map will prevent the auto-focus or slewing function locking on a hot pixel rather then on a star. The bad pixel map will be only applied on preview images, focus or slewing images. It is not applied on captured images. Those images are not altered. Use the menu **File → Bad pixel map → Apply to current image** If you want to apply the bad pixel map to an image you load in the program.\\ You can identify an image that was BPM processed with a comment at the end of the FITS header. ====Information==== This menu show information about the current bad pixel map, the number of bad pixel and the size of the image it was taken from. You have two options to create, using the camera directly or using a processed dark frame. The second option is preferred because the processed dark as less noise and you can use a lower [[preferences#preview|sigma]] value to detect fainter deviant pixels. ====Create from the camera==== Procedure: - Camera should be connected and cooling on if available. - Set the required binning in [[preview|Preview tool]]. Use the same binning as for the focus and slewing - Select an exposure time between 10 and 60 seconds. - Cover the camera or telescope similar as taking a dark image. If your camera has a shutter it will remain closed during the exposure. - Select menu **File → Bad pixel map → Create from camera** - Click Continue. A dark will be taken and number of hot pixels will be reported in the log window. {{:en:documentation:bpm_create.png| }} ====Create from a dark file==== Select menu **File → Bad pixel map → Create from dark file** Select the dark file from the file dialog. ====Clear the bad pixel map==== To remove/clear the bad pixel map select the menu **File → Bad pixel map → Clear bad pixel map** ====Check the bad pixel map==== Take a preview image and check if the bright hot pixels are suppressed. Or open a saved raw image and use the menu **File → Bad pixel map → Apply to current image** If you still see some not removed hot pixel you can retry the procedure after setting a lower value for [[preferences#preview|sigma]].
====Possible errors==== **Error:** If you get an error message: "too many hot pixels", increase the sigma threshold value in the menu **Edit → Preferences → [[preferences#preview]]** options. If successful the program log will report the number of hot pixels suppressed. {{:en:documentation:bmp-threshold.png|}}. \\ A typical threshold value is 5 for CCD and 8 for a modern CMOS sensors. Decrease the threshold value if you want suppress more hot pixels. Normally you should suppress maybe 5 to 30 hot pixels but you can go much higher. With some camera it is not possible to get a good result here. In this case use a [[dark frame]] instead.