Calibrate digital photographs

Image selection
Calibration-settings
Set camera orientation for portrait formats
Select suitable Calibration-Sets
Start calculation

Image selection

Clicking the button "Add images" on the main window or alternatively File >> Calibrate images opens following dialog:

Calibrate images

Click the button Add images... in order to add images, which shall be calibrated, to the list using the image file browser. Within this browser you can preview all supported image formats as well as some image information.

Image file browser

Alternatively you can add images to the list by drag&drop directly from the Windows-Explorer or another image browser.


Calibration-settings

High Quality: When this is checked, the selected images are undistorted in HQ mode, otherwise in LQ mode.
Trim frame: If this is not checked, the image is undistorted maintaining all picture information, which however becomes apparent by frayed edges.
Correct vignetting: If this box is checked, the vignetting is removed.
Please note that the result quality strongly depends on the diversity of the Calibration-Pictures which have been used to create the corresponding Calibration-Set. The more different f-stops per focal length have been available, the more precise the vignetting can be removed.
In case that the Calibration-Set has been created with only one single f-stop per focal length, e.g. as manual adjusting is not allowed with the camera, the result may be quite unreliable.
Zoom factor: The zoom factor affects the size of the calibrated images. If the size shall fit the source image size, the zoom factor is "1".
Transfer metadata: When this setting is enabled, all EXIF-information (if the target format allows) will be transfered from the source image to the calibrated image, and the calibrated image will be marked as calibrated.
Notice: when disabled, the image is not protected against accidently repeated calibration!
(This feature uses "exiftool.exe" by Phil Harvey).
Image output format: Graphic file format for the calibrated images. In most cases the jpeg-format with a quality of 95 is sufficient. However if the image shall be processed following the ImageIron calibration, a lossless image file format (e.g. tiff) or a higher jpeg quality should be preferred.
It is recommended to save the image in a lossy format just once, after all process steps and for archiving.
Convert to 8 bpc: If this option is checked, images with a color depth of 16 bit per color channel are converted down to a color depth of 8 bit. This checkbox is only enabled if the output format supports the 16-bit mode.
Select destination folder: Select the save location for the calibrated images.

Set camera orientation for portrait formats

In contrast to the Calibration-Pictures, it is allowed to rotate the images to be calibrated by 90 respectively -90 before the ImageIron calibration process. To remove the distortion in the HQ-mode, ImageIron must however be informed about the camera orientation, in which each picture has originally been taken (because removing distortion and vignetting is not performed symmetrically about the image center point).

For this purpose, the picture edges (right or left), which correspond to the camera bottom, must be marked. If, for example, the photographer turns his camera around 90 counter clockwise for the shot, then the right picture edge must be marked as "Bottom".

Since most photographers usually turn the camera into one certain direction by habit, a default rotation direction can be defined with the two radio buttons 90 clockwise and 90 counter clockwise. If some pictures were taken with a different camera orientation, then these can be adjusted individually with the "Bottom" marks on the left and the right edge of the preview image by mouse click (also possible with multiple selected images).


Select suitable Calibration-Sets

Normally the Calibration-Sets can be assigned to particular images automatically. The images which have been uniquely assigned are marked with a green point .

If a picture, which is marked with a green point, is selected, then a small distortion preview is displayed in the right, upper corner of the calibration window. When the mouse enters the control respectively leaves it, the view swaps.

For certain images possibly several suitable Calibration-Sets are found. These images are marked with a yellow point ).
This is the case if several Calibration-Sets have been created for the same camera/lens-combination or if the image contains insufficient EXIF-data to identify the camera which has been used to take the picture.

A green point with an exclamation mark indicates, that indeed the Calibration-Set allocation was successful, however still some data (focal length, f-stop or perhaps a shift-setting) must be completed manually.

A red point with an exclamation mark in it marks the images which contain enough EXIF-information about the used camera, but could not be assigned to an existing Calibration-Set.

As only clearly assigned images can be calibrated, the red or yellow marked images must be assigned manually to a Calibration-Set:
Clicking the context menu entry Complete information opens a selection list of possible Calibration-Sets where the user can choose an entry at his own discretion.
In particular when manually assigning red marked images the user should know exactly, what he is doing, since an unsuitable Calibration-Set sometimes can distort the image additionally.


Start calculation

Start the calibration with the current settings by using the button Calibrate images!.

After successful calibration of an image, an according comment is added in the EXIF property "Image-Description". Thus the image is protected against accidental repeated calibration runs. Note that this feature is only supported under the condition, that Transfer metadata is enabled, and that an image format is used, which supports EXIF meta data (jpg or tiff).

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