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Wednesday, August 6, 2014

What tools are available in PhotoFlow?

If you are wondering what kind of image editing can be performed with the current version of PhotoFlow, this post should give you some useful guidelines.

PhotoFlow is far from being a complete photo retouching software, but it already provides several of the "classical" tools.

Here is a brief list of the tools that are already implemented and working:
  • RAW image processing: 
    • Files from most of the existing cameras with bayer sensors can be loaded and processed. 
    • The demosaicing is based on the Amaze or IGV algorithms and is directly derived from RawTherapee code.
    • The basic RAW processing tools are provided: exposure compensation, white balance (limited to camera WB, sport WB and "color" spot WB for the moment), and camera color processing.
  • Raster image loading: photoflow can load raster images in TIFF and JPEG format, and  applies any embedded icc profile that is found in the image metadata.
  • The basic tools for color processing are available:
    • "invert" tool
    • "brightness-contrast" tool: the classic tool for changing the overall brightness and/or contrast of the image. It is still a bit buggy, but mostly functional...
    • "curves" tool: this is in my opinion the "swiss army knife" of image editing, and several other tools (invert, brightness-contrast, levels, etc...) can be realized using appropriate curves... the tool is implemented in a quite complete way: separate curves can be applied to the different image channels, controls points can be added and removed, their position can be changed by dragging the mouse or setting the input and output values by numbers. The main thing which is missing is the possibility to set the control points by clicking in the input image with the mouse. Here is an example of how the curves tool looks like:
    • "desaturate" tool
    • "channel mixer" tool: it computes a given mixture of the RGB channels and copies the result into a target channel(s). For the moment the result is copied into all three RGB channels the same way, thus producing a grayscale image. This is a simple and flexible way to convert an image into B/W.
  • Colorspace conversion: photoflow is designed to be able to edit images in RGB, gayscale, Lab and CMYK colorspaces, and to provide tools to convert between those colorspaces on-the-fly. Presently only conversions to Lab and sRGB colorpsaces are fully functional.
  • Image geometry: resizing, cropping and rotation are foreseen in future versions; only a preliminary crop tool is available at the moment
  • Hand drawing: photoflow includes a simple tool for hand drawings, using a pencil with user-selectable size, color and opacity. This is particularly convenient for creating custom masks for the local application of other editing tools.
  • Blurring & sharpening: photoflow include the well-known gaussian blur and unsharp mask tools; other sharpening methods (like RL deconvolution) will be included in the future.

As you can see, photoflow includes a minimal set of tools which probably covers 90% of the photo editing needs, unless you go for some heavy retouching beyond local and global color and contrast adjustments, sharpening and B/W conversion. Moreover, the set of available tools is constantly growing. The first items on the TODO list are:
  • Improvement of the curves tool, in particular the addition of control points via direct mouse clickinginside the image
  • Resizing and rotation tools, and improvement of the cropping tool
  • Addition of false color correction to the RAW data demosaicing
  • "Clone stamp" tool
  • Several performance improvements
  • Lots of bug fixes
  • ...

In future blog posts I will give tutorials and examples of usage of the different tools, and news about new tools or improvements of the existing ones. You will also find useful informations in the photoflow's wiki.


  1. PhotoFlow is a free, open-source non-destructive photo retouching program that provides a complete RAW image editing workflow. It is similar to Darktable or RawTherapee, and it already integrates a large number of filters from GMIC.

  2. digiKam is an advanced digital photo management application and one of the perfect alternatives to PhotoFlow which makes importing and organizing digital photos a snap. The photos are organized in albums which can be sorted chronologically, by folder layout or by custom collections. You will get so many photo editing tools with the app.