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--- doc:appunti:hardware:olympus-e-m10:raw_processing [2023/01/02 17:09] – [Sharpening] niccolo
+++ doc:appunti:hardware:olympus-e-m10:raw_processing [2023/01/27 10:57] – niccolo
@@ Line 20: / Line 20: @@
 In this article I will analyze what should be a RAW processing workflow using my **Olympus E-M10 Mark II** with some **Olympus M.Zuiko** lenses and some third party **manual lenses**, using the **OM Workspace** software and other software that you can run un **GNU/Linux**, like **[[https://www.dechifro.org/dcraw/|dcraw]]** and **[[http://www.rawtherapee.com/|RawTherapee]]**.
-FIXME
 ===== OM Workspace =====
@@ Line 51: / Line 50: @@
 </code>
-RAW development performed by OM Workspace is called **PC RAW processing** because it is performed by the PC. With some Olympus cameras it is possibile to perform the so called **USB RAW processing**, i.e. the processing is performed by the camera graphic processor (generally the Olympus TruePic) via the USB cable. The camera must be turned on and switched to the **RAW/Control** mode. The E-M10 is not capable of such mode.
+{{ olympus-raw-control.jpg?160|}}
+RAW development performed by OM Workspace is called **PC RAW processing** because it is performed by the PC. With some Olympus cameras it is possibile to perform the so called **USB RAW processing**, i.e. the processing is performed by the camera graphic processor (generally the Olympus TruePic) via the USB cable. The camera must be turned on and switched to the **RAW/Control** mode (see the picture of the USB menu on the right). Unfortunately the E-M10 is not capable of such mode.
-===== Darktable =====
+===== RawTherapee =====
-FIXME
+The program uses a clever procedure to open a RAW image for editing: it searches for the embedded thumbnail into the RAW file and it builds a tone curve on-the-fly to match the RAW data to the jpeg. This generally will assure that the program can open a RAW picture with no specific knowledge of the camera model. Thid default behaviur is controlled by the //Preferences// => //Image Processing// => //Default Processing Profile// => //For raw photos//: **Auto-Matched Curve ISO Low**.
-===== RawTherapee =====
+For the Olympus E-M10 the thumbnail embedded into a RAW file is a JPEG file with a resolution of **3200 x 2400** pixels and about **1 Mb** in size (you can extract if using the ''dcraw'' program).
+==== How To ====
+  * **Export cooked image file**:
+    - Into the Editor apply the required cooking processes using the **Toolbox tabs** on the right side (//Exposure//, //Detail//, etc.)
+    - A checkmark icon appears over the thumbnail, this means that the image is processed (a sidecar ''.pp3'' file is saved along the RAW image); click the //Save current image// icon below the edit screen.
+  * **Restore RAW image to default state**
+    * In the File Browser right-click the image and select //Processing file operations// => //Clear//.
+    * Otherwise, when the program is closed, you can delete the sidecar ''.pp3'' file where RawTherapee saves the development procedure.
+  * **Delete image files**:
+    - From the File Browser click the //Move to trash// icon above the image thumbnail.
+    - Click the //Show contents of trash// icon on the filter toolbar.
+    - Click the //Permanently delete all files in trash// on the left of the thumbnails view.
+==== The default cooking ====
+I made a simple test opening a RAW file and **changing the white balance** from the in-camera preset to //shade//, no other changes were applied to the image. The image is then saved with JPEG quality 98 and //best quality// subsampling. Here it is a 8x zoom detail, compared with the in-camera JPEG. As you can see the **noise reduction** applied in-camera is significantly higher than the one used by RawTherapee:
+{{.:rawtherapee:develop-default-rawtherapee.jpg?240|RawTherapee default RAW processing}}
+{{.:rawtherapee:develop-default-in-camera.jpg?240|In-camera JPEG}}
+===== Darktable =====
 FIXME
@@ Line 161: / Line 183: @@
 You can use this purely indicative table as a starting point for your own experiments:
-^ Olympus noise filter  ^ Dcraw wavelet denoising threshold\\ (empirical estiamte)  ^
+^ Olympus noise filter  ^ Dcraw wavelet denoising threshold\\ (empirical estimate)  ^
 | low       |   50 |
 | standard  |  200 |
 | high      |  300 |
+==== Chromatic aberration ====
+FIXME
@@ Line 206: / Line 232: @@
 {{.:dcraw:dcraw-magick-in-camera.jpg?180|In-camera JPEG}}
 {{.:dcraw:dcraw-magick-raw.jpg?180|dcraw only}}
-{{.:dcraw:dcraw-magick-bright-contrast.jpg?180|dcraw and ImageMagick tonal adjust}}
+{{.:dcraw:dcraw-magick-bright-contrast.jpg?180|dcraw and ImageMagick manual tonal adjust}}
 If you want to roughly compare the in-camera developed JPEG and the image produced by ImageMagick (concerning brightness and contrast), you can get the overall image statistics using the **identify** command provided by ImageMagick itself. Check for the **[[wp>Mean|mean]]** and **[[wp>Standard deviation|standard deviation]]** values (where the value in parenthesis are normalized into the interval 0-1); a low mean value means a low brightness, a low standard deviation value means a low contrast:
@@ Line 234: / Line 260: @@
 </code>
-The following three enlargements show the sharpening of the **in-camera JPEG**, the RAW developed with **tonal adjust and no sharpening** and the RAW developed with **tonal adjust and sharpening**:
+The following three enlargements show the sharpening of the **in-camera JPEG**, the RAW developed (dcraw + ImageMagick) with **tonal adjust and no sharpening** and the RAW developed with **tonal adjust and sharpening**:
 {{.:dcraw:sharpen-in-camera.jpg?200|In-camera JPEG sharpening}}
 {{.:dcraw:sharpen-none.jpg?200|RAW development with no sharpening}}
 {{.:dcraw:sharpen-imagemagick.jpg?200|RAW development and ImageMagick adaptive-sharpen}}
+==== Barrel distortion ====
+JPEG images produced in-camera have generally the lens distortion corrected by the camera firmware, using data provided by the lens itself. ImageMagick is capable to apply a **barrel distortion correction** to an image, but it must to know **three parameters** which are **closely related to the specific lens** and to the **focal length** used (if the lens is a zoom with a variable focal length).
+There are some free and open source documents about distortion parameters for lenses produced by well known makes, the main one is the **[[https://sourceforge.net/projects/lensfun/|Lensfun]]** database. Unfortunately it does not contain data about my Olympus M.Zuiko 12-42 mm pancake lens, so I haven't been able to try the ImageMagick incantation.
+It is possible to reverse engineer the barrel distortion applied by the camera body by comparing the RAW image and the in-camera JPEG. For a zoom lens you have to make several comparison at different focal lengths and calculate the distortion coefficients using a regression formula. See this article: **[[https://legacy.imagemagick.org/Usage/lens/|Introduction to Lens Correction]]**.
+So - at the moment - **I'm not able to apply lens distortion correction to RAW images** using dcraw and other **command line tools**.
+==== Vignetting ====
+For the correction of **[[wp>Vignetting|vignetting]]** effect, the same considerations made for the barrel distortion error apply. In-camera JPEGs are corrected by the camera firmware using specific data provided by the lens itself. ImageMagick is capable to apply the **vignette** filter, but you must to provide the correct parameters. Unfortunately the parameters are tied to the **lens make and model**, the **focal length**, the **focal distance** and the **aperture** in use!
 ===== Picture mode =====