PanGazer logo PanGazer – saving images

Introduction

Download PanGazer


Getting started

General settings

Setting North

Saving views

Saving images

Sharing images

Image geography

Show image location

Overlays

Enhancements

Aspect ratio


Making panoramic images

Keyboard shortcuts

Command line options

The gnomonic projection

Thanks

PanGazer lets you save the current image file. To do this, you can either:

  • select the Image → Save image as ... menu item (or press ‘Ctrl-S’): this will open the usual Windows file save dialog box for saving the image

  • select the Image → Resize image and save as ... menu item (or press ‘Ctrl-R’): this will first open a PanGazer dialog box (see below) that lets you change the size of the image before saving and also lets you expand a part-spherical panorama to a full sphere (as required for some sharing platforms – see Sharing Images for more details).

In either case, the image is written to the selected file as a JFIF (JPEG File Interchange Format) file with extension .jpg or .jpeg, including the Exif (Exchangeable image file) metadata, XMP (Extensible Metadata Platform) metadata, and any other metadata that was loaded for the current image. The Exif and XMP metadata might be updated or replaced, as detailed below.  Note that if the image being saved is spherical then new XMP metadata are always written; in this case the XMP metadata requires a North value (see the Setting North page) so, if North has not been set explicitly, PanGazer will set North at the centre of the image in the XMP metadata but will not assume that value for North on loading the image.

If the original image was not a JPEG image or if the image had to be re-compressed for any reason then a JPEG Quality of 90% is used.

The PanGazer ‘Save image’ dialog box

Here is a screenshot of the PanGazer Save image dialog for a part-spherical image (for non-spherical images, or full-sphere images, the line with the checkbox is replaced by a description of the image type):

PanGazer screenshot showing save dialog

PanGazer screenshot showing save dialog

In detail:

  • You can adjust the size of the image by editing either the X: or Y: values (PanGazer will update the other to maintain the same aspect ratio, if the new value is valid). You can reset the X and Y values to those of the current image by clicking the Reset button.

    Note that if the image will be a full-sphere panorama then the X value must be even (so that the Y value can be exactly half that).

  • You can convert the image to a full sphere if it is a part-spherical panorama (e.g., an image that was created from drone photographs that had limited coverage above the horizon, such as the PanGazer ‘starter image’). To do this, check the Expand this 360° image to full sphere before save checkbox (this will be checked by default for a part-spherical image).

    PanGazer will then create a new image and fill in any missing data above the top edge (and also one column of data if the X dimension is odd) using deterministic interpolation and smoothing to reduce sharp edges and generally improve the visual appearance.

    This is useful for some applications which require that 360° images are ‘full spheres’ (that is, the image has data from 90° below to 90° above the horizon) – see Sharing Images for more details.

  • If you make no changes to the input fields and uncheck the checkbox then the image will be saved as-is, with updated metadata if you have changed the view, image geography, etc. (that is, as though Save image as ... had been used).

Having made any desired changes, click the Save button. This will create a resized and expanded image, if necessary (this may take a few seconds), and then ask where it should be saved using the usual Windows file save dialog.

If any changes to the image size were made:

  • The saved image is opened in a new window so you can check it (and, perhaps, adjust the viewpoint or other information and re-save it).

  • PanGazer cannot simply duplicate the original Exif and XMP metadata. Instead, selected “well-known” values are copied from the current Exif metadata (see saving views for the list of copied numbers and strings), and values you have set are included or updated (see below). If the image is spherical then new XMP metadata matching the new image are written, also as described below.

Saved data

PanGazer updates the following Exif metadata on saving if the values are known or changed (e.g., set using the geography dialog):

  • latitude and longitude of the image (camera location)

  • elevation of the image (altitude of the camera above mean sea level)

  • bearing of the centre of the image (relative to True North; 0° to, but not including, 360°).

  • the pitch (tilt) of the centre of the image (0° if at the horizon, positive above or negative below).

If the image is spherical then new XMP metadata are written, including:

  • image geometry (X and Y for equirectangular full sphere, etc.)

  • the bearing of the centre of the image (relative to True North; 0° to, but not including, 360°); this requires a valid North value (see the Setting North page) – if North has not been set then PanGazer will assume that North is at the centre of the image so that the initial view angles can be saved (see below); this does not set the North bearing in the Exif data

  • the pitch (tilt) of the centre of the image (0° if at the horizon, positive above or negative below)

  • the view angles (bearing relative to True North and tilt relative to the horizon) and zoom setting currently in use; these will be used for the initial view of the image when first loaded – that is, the current bearing and tilt of the view will appear at the centre of the initial view window, zoomed as saved, whenever the saved image is loaded by PanGazer (or other applications that use the XMP initial values metadata).

Note that the view angles and zoom are also saved as local persistent data when PanGazer is closed, and those saved values will be used when PanGazer is next started and will override values from the XMP metadata. The initial view values from the XMP metadata are, therefore, only used when the image was not the last image viewed using PanGazer, or if you select the Reset viewpoint menu item from the View menu or from the pop-up menu, or you press the ‘r’ key.

PanGazer and these web pages were written by Mike Cowlishaw; Please send me any corrections, suggestions, etc.
All content Copyright © Mike Cowlishaw, 2014–2021, except where marked otherwise. All rights reserved. The pages here, and the PanGazer program, are for non-commercial use only.
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This page was last updated on 2021-07-13 by mfc.