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0001 .. meta::
0002    :description: digiKam Image Editor Settings
0003    :keywords: digiKam, documentation, user manual, photo management, open source, free, learn, easy, setup, configure, image, editor, corrections, raw, workflow, demosaicing, versioning, save, white, balance
0004 
0005 .. metadata-placeholder
0006 
0007    :authors: - digiKam Team
0008 
0009    :license: see Credits and License page for details (https://docs.digikam.org/en/credits_license.html)
0010 
0011 .. _editor_settings:
0012 
0013 Image Editor Settings
0014 =====================
0015 
0016 .. contents::
0017 
0018 .. _window_settings:
0019 
0020 Editor Window Settings
0021 ----------------------
0022 
0023 By default the Image Editor will use a black background behind photographs when they are displayed. If you prefer a different background color, with the options **Use theme background color** and **Background color** you can choose one here.
0024 
0025 You can also turn off the different elements when the Image Editor is in full screen mode, as the ToolBar, the Thumbbar, the Sidebar, and the Statusbar.
0026 
0027 **Over-exposure**  and **under-exposure** settings can highlight areas of an image to indicated by dark and light marker colors that can be defined here. In the editor this viewing mode can be switched on and off with :kbd:`F11` and :kbd:`Ctrl+F11` respectively. The thresholds for over-exposure and under-exposure can be set by the adjustment bars "... percents". Check Indicate exposure as pure color if you want only pure black (RGB 0,0,0) indicated as under-exposure and only pure white (RGB 8 bit 255,255,255 respectively RGB 16 bit 65535, 65535, 65535) indicated as over-exposure.
0028 
0029 The option **Restore the settings of the Image Editor tools** can be used to restore the settings of the Image Editor tools from the last session. Otherwise, the default settings will be used.
0030 
0031 .. figure:: images/setup_editor_iface.webp
0032     :alt:
0033     :align: center
0034 
0035     The digiKam Image Editor Windows Configuration Page
0036 
0037 .. _versioning_settings:
0038 
0039 Image Versioning Settings
0040 -------------------------
0041 
0042 Non-Destructive Editing and Versioning gives you the freedom of editing your images, trying out whatever you want without worrying that you might regret later what you did. digiKam takes care of the original and every important intermediate step if you want.
0043 
0044 .. figure:: images/setup_editor_version.webp
0045     :alt:
0046     :align: center
0047 
0048     The digiKam Image Versioning Configuration Page
0049 
0050 In the checkbox at the top you can **Enable Non-Destructive Editing and Versioning** feature globaly.
0051 
0052 In the first field **Save files as**, you can choose the file format used for saving the intermediate steps and the final result. Remember that **JPEG** is a lossy format. So if you need to start over from an intermediate step it wouldn't be really non-destructive. If you can afford it in terms of space on the harddisk and loading/saving speed you better choose a lossless format like **PNG** or **PGF** for instance. Please click the information button on the right side for more detailed information.
0053 
0054 In the next field you can decide whether the application will save changes automatically **When Closing Editor** or should ask first.
0055 
0056 In the third field named **Keep a snapshot of an edited image**, you decide on which occasions you want the editor to save intermediate steps. Please click the information button on the right side for more detailed information.
0057 
0058 In the last field you can adjust whether you want only the last version to be shown from the Icon-View visible **In Main View** (default, none of the boxes checked) or if you also want to see icons of the original version and/or intermediate steps.
0059 
0060 .. _saveimage_settings:
0061 
0062 Save Image Settings
0063 -------------------
0064 
0065 When changes are made to JPEG files and they are saved back to the hard disk the JPEG file must be re-encoded. Each time a JPEG file is encoded a decision must be made on the level of **JPEG quality** that is to be applied. Unfortunately the level of quality applied is not recorded in the image file. This means that the Image Editor cannot use the same quality ratio when saving an altered image as was used for the original image. You can change the default level of quality that the Image Editor will apply when it saves altered images by moving the JPEG quality slider (1: low quality / 100: high quality and no compression). JPEG metadata is fully supported.
0066 
0067 **Chroma subsampling** is the practice of encoding images by implementing more resolution for luminance information than for color information. Please read this Wikipedia article for a full explanation.
0068 
0069 .. figure:: images/setup_editor_save.webp
0070     :alt:
0071     :align: center
0072 
0073     The digiKam Default File Save Configuration Page
0074 
0075 With **PNG compression** option, you can reduce PNG image files size. This operation does not reduce image quality because PNG uses a lossless algorithm. The only effect is that image data needs more time to compress/decompress. If you have a fast computer you can change this value to use a high compression factor (1: low compression / 9: high compression), and metadata is supported.
0076 
0077 With **Compress TIFF** option, you can toggle to use Deflate compression algorithm with TIFF image files. This will reduce TIFF image files sizes. It has no image quality effect because Deflate is a lossless algorithm and metadata is supported.
0078 
0079 With the **LossLess JPEG 2000** files option allows for lossless storage, or, if the lossy options is selected, even then the quality for comparative files size is much better than normal JPEG, and metadata is supported.
0080 
0081 With the **LossLess PGF files** option allows for lossless storage, or, if the lossy options is selected, even then the quality for comparative files size is much better than normal JPEG-2000 and very fast to process encoding, decoding and metadata is supported.
0082 
0083 With the **LossLess HEIF files** option allows for lossless storage, or, if the lossy options is selected, even then the quality for comparative files size is much better than normal JPEG-2000, but it slower to encode and decode and it supports only 8-12 bits colors depth. This image format dedicated to replace JPEG on smartphones, not all metadata is supported.
0084 
0085 With the **LossLess WEBP files** option allows for lossless storage, or, if the lossy options is selected, even then the quality for comparative files size is much better than normal JPEG-2000, but it only support 8 bits colors depth. This image format dedicated to replace PNG and JPEG on the Internet, not all metadata is supported.
0086 
0087 With the **LossLess AVIF files** option allows for lossless storage, or, if the lossy options is selected, even then the quality for comparative files size is much better than normal JPEG-2000, but it slower to encode and decode and it support only 8-12 bits colors depth. This image format dedicated to be a concurrent of HEIF, not all metadata is supported.
0088 
0089 When the option **Show Settings Dialog when Saving Image Files** is checked, digiKam will show a dialog where settings can be changed when saving image files, else default settings are used when saving image files.
0090 
0091 .. _setup_raw:
0092 
0093 RAW Behavior
0094 ------------
0095 
0096 In the early versions of digiKam the Image Editor was just a viewer for photographs, but it is rapidly developing into a very useful photo manipulation tool. This dialog allows you to control how the Image Editor will behave when opening RAW files.
0097 
0098 .. figure:: images/setup_editor_raw_behavior.webp
0099     :alt:
0100     :align: center
0101 
0102     The digiKam RAW Behavior Configuration Page
0103 
0104 **Fast and simple, as 8 bit image**: RAW files will be decoded to 8-bit color depth with a BT.709 gamma curve and a 99th-percentile white point. This mode is faster than 16-bit decoding. In 8-bit mode only the Auto Brightness setting will be taken into account.
0105 
0106 **Use the default settings, in 16 bit**: If enabled, all RAW files will be decoded to 16-bit color depth using a linear gamma curve and according to the settings in the **RAW Default Settings** tab. To prevent dark image rendering in the editor, it is recommended to use Color Management in this mode.
0107 
0108 **Always open the Raw Import Tool to customize settings**: With this option you can select which Raw Import Tool will used to open RAW files. Raw processing tools available are:
0109 
0110     - **Import RAW using LibRaw**: the default plugin for digiKam which will provide a fully integrated module at the Right Side Bar in the Image Editor where you can set individual parameters for every image you open.
0111 
0112     .. figure:: images/setup_editor_raw_import.webp
0113         :alt:
0114         :align: center
0115 
0116         The digiKam RAW Import Tool Processing a Nikon NEF File
0117 
0118     - **RawTherapee**: this application must be installed on your computer. `RawTherapee <https://en.wikipedia.org/wiki/Darktable>`_ is application software for processing photographs in RAW image formats, as created by many digital cameras. It comprises a subset of image editing operations specifically aimed at non-destructive post-production of raw photos and is primarily focused on improving a photographer's workflow by facilitating the handling of large numbers of images.
0119 
0120     - **UFRaw**: this application must be installed on your computer. `UFRaw <https://en.wikipedia.org/wiki/UFRaw>`_ is an application which can read and manipulate photographs in RAW image formats, as created by many digital cameras.
0121 
0122     - **DarkTable**: this application must be installed on your computer. `Darktable <https://en.wikipedia.org/wiki/Darktable>`_ is a free and open-source photography application program and RAW developer. It comprises a subset of image editing operations specifically aimed at non-destructive RAW image post-production.
0123 
0124     .. figure:: videos/setup_editor_raw_behavior.webp
0125         :width: 500px
0126         :alt:
0127         :align: center
0128 
0129         Screencast of RAW Import Tool Pre-Processing a Digital Negative in DarkTable
0130 
0131 .. _setup_rawdefault:
0132 
0133 RAW Default Settings
0134 --------------------
0135 
0136 .. note::
0137 
0138     These default settings is used only with the LibRaw interface.
0139 
0140 Demosaicing
0141 ~~~~~~~~~~~
0142 
0143 .. figure:: images/setup_editor_raw_demosaicing.webp
0144     :alt:
0145     :align: center
0146 
0147     The digiKam Default RAW Demosaicing Configuration View
0148 
0149 A `demosaicing algorithm <https://en.wikipedia.org/wiki/Demosaicing>`_ is a digital image process used to interpolate a complete image from the partial raw data received from the color-filtered image sensor internal to many digital cameras in form of a matrix of colored pixels. Also known as CFA interpolation or color reconstruction.
0150 
0151 **Interpolate RGB as four colors**: The default is to assume that all green pixels are the same. If even-row green pixels of the sensor are more sensitive to ultraviolet light than odd-row this difference causes a mesh pattern in the output; using this option solves this problem with minimal loss of detail. To resume, this option blurs the image a little, but it eliminates false 2x2 mesh patterns with VNG quality method or mazes with AHD quality method.
0152 
0153 **Do not stretch or rotate pixels**: For Fuji Super CCD cameras, show the image tilted 45 degrees. For cameras with non-square pixels, do not stretch the image to its correct aspect ratio. In any case, this option guarantees that each output pixel corresponds to one RAW pixel.
0154 
0155 **Quality**: digiKam offer us many alternatives e.g the most common are **Bilinear**, **VNG**, and **AAHD** interpolations. It seems that AAHD (for Ameliored Adaptive Homogeneity-Directed) is the best choice for quality according to some test that we have performed and the paper of the person that implemented it. This improved method based on **AHD** interpolation, selects the direction of interpolation so as to maximize a homogeneity metric, thus typically minimizing color artifacts. VNG (for Variable Number of Gradients) was the first algorithm used by libraw but suffers from color artifacts on the edge. Bilinear is interesting if you are looking for speed with a acceptable result. **PPG** (for Patterned-Pixel-Grouping) is a pixel grouping interpolation that uses assumptions about natural scenery in making estimates. It has fewer color artifacts on natural images than the VNG method. Considerate **DCB** and **DHT** interpolation as experimental method.
0156 
0157 **Pass**: Set here the passes used by the median filter applied after interpolation to Red-Green and Blue-Green channels.
0158 
0159 **Refine interpolation**: For DCB interpolation only, turn on the enhance interpolated colors filter to improve sharpness.
0160 
0161 White Balance
0162 ~~~~~~~~~~~~~
0163 
0164 .. figure:: images/setup_editor_raw_wb.webp
0165     :alt:
0166     :align: center
0167 
0168     The digiKam Default RAW White Balance Configuration View
0169 
0170 **Method**: Four options are available here: **Default D65**, **Camera**, **Automatic**, and **Manual**. *Default D65* reflects normal daylight conditions. *Camera* uses the camera's custom white-balance settings if set. *Automatic* uses by default a fixed color balance based on a white card photographed in sunlight. *Manual* will adjust colors according to the **T(K)** (for color temperature in degrees Kelvin) and the **Green** settings to set the green component adjusting the magenta color cast removal level.
0171 
0172 **Highlights**: Default is here to consider highlights (read: part of your images that are burned due to the inability of your camera to capture the highlights) as plain / **Solid white**. You can get some fancy results with the unclip option which will paint the highlights in various pinks. At last you can try to consider recovering some parts of the missing information from the highlights with **Rebuild** option. This is possible because the blue pixels tends to saturate less quickly than the greens and the reds. digiKam will try to reconstruct the missing green and red colors from the remaining none saturated blue pixels. Of course here everything is a question of tradeoff between how much color or white you want. If you select Reconstruct as the option, you will be given the choice to set a **Level**. A value of 3 is a compromise and can/should be adapted on a per image basis. **Unclip** leave highlights unclipped in various shades of pink, and **Blend** clipped and unclipped values together for a gradual fade to white.
0173 
0174 **Exposure Correction (E.V)**: Turn on the exposure correction before interpolation which can be applied with a **Linear Shift** level. Amount of **Highlight** preservation can be also adjusted but only if shift correction is > 1.0 E.V.
0175 
0176 **Correct False Colors In Highlights**: If enabled, images with overblown channels are processed much more accurately, without 'pink clouds' (and blue highlights under tungsten lamps).
0177 
0178 **Auto Brightness**: If disable, use a fixed white level and ignore the image histogram to adjust brightness.
0179 
0180 Corrections
0181 ~~~~~~~~~~~
0182 
0183 .. figure:: images/setup_editor_raw_corrections.webp
0184     :alt:
0185     :align: center
0186 
0187     The digiKam Default RAW Corrections Configuration View
0188 
0189 **Noise Reduction** can be applied while demosaicing your image at a slight speed penalty. This option applies a noise reduction algorithm while the image still is in CIE Lab color space. Because the noise is only applied to the Luminosity layer (the *L* of the Lab), it should not blur your image as traditional noise reduction algorithms do in RGB mode. If you converted an image from RAW and it appears noisy, rather than applying a denoiser, go back and re-convert with this option enabled.
0190 
0191 You can select a noise reduction method to apply during RAW decoding. **None** do not apply the noise reduction. **Wavelets** apply after interpolation a wavelets correction method to erase noise while preserving real details. **FBDD** for Fake Before Demosaicing Denoising is an experimental noise reduction method applied before interpolation.
0192 
0193 The defaults **Threshold** value is 100. Higher values will increase the smoothing, and lower values will decrease it.