Raw Images

Starting from 0.4.0, Photovault supports raw files from most cameras. You can crop, rotate and annotate raw images just as normal images. In addition, you can adjust the colors and exposure of raw photos in wasy that is not possible for other image file types.

This flexibility and control is the advantage of using raw image files. Camera CCD sensor captures much wider dynamic range of light than what can be presented on computer screen and stored into a JPEG file. Raw files contain all of this information and you can later decide how it is rendered into an image.

There are also disadvantages: raw files take much more disk space and are considerably slower to display. The additional control possibilities mean more work to you.

Pre-requisites

Photovault uses dcraw by Dan Coffin for reading raw files. Unlike Photovault, which is platform independent Java application, dcraw must be compiled for every processor type and operating system separately. Photovault distribution contains dcraw executables for Windows and Linux (in x86 hardware). If you are using some other operating system, see UserSuppliedDcraw.

Also, to get best possible color quality you should have color profile for your camera. This is a file, typically with extension ".icc", that describes how the camera CCD sensor responds to different colors. Without this file dcraw and photovault use linear color matrix to get approximate colors. Usually the result is quite OK but proper ICC profile will give more control and better colors.

Finding ICC profile for your camera can be challenging. You can find ICC files with the software that comes with many cameras. For some cameras there are ICC profiles available in Internet. You can also make an ICC profile by yourself.

Importing Raw Images

There is nothing special in importing raw images - Photovault indexes them and creates thumbnails just the same way as for normal images. In addition, Photovault tries to set the conversion parameters automatically to initial values. These are seldom the optimal ones but give a good starting point. More specifially Photovault uses these settings:

• For color balance Photovault uses settings that are recommended in the raw file. Typically cameras have an automatic white balance estimation algorithm that gives good starting point.
• Photovault adjusts exposure based on average brightness in the raw file. This will give good results for normal-gain images but will darken wery light images and lighten dark ones.
• Photovault will do also some adjustment to image contrast to preserve detail in the brightest areas.

After you have imported the images you can annotate, crop and rotate the images normally.

Adjusting Colors

To start adjusting colors, select the image in thumbnail pane and either select "Adjust colors..." from Image menu (or right-mouse popup menu) or press the corresponding icon in toolbar.

This opens the color adjustment dialog. You can change the settings either by dragging the sliders or entering numerical values to the text fields on right side of sliders.

The settings that can be adjusted try to roughly emulate the controls a photographer could use in darkroom.

Exposure

Exposure setting controls the brightness of the converted image. Change of one unit has similar effect as over or underexposing by 1 f-stop.

Compress highlights

Inclreasing highlight compression has very small effect to dark and midtones but darkens bright areas and bring detail to highlights that would otherwise show as pure white.

Setting highlight compression to negative value adds contrast to the image

Color temperature

Color temperature changes the color balance of the image. Smaller values make the image more blue or "colder", larger values add orange or make the image "warmer".

Green gain

Color balance adjusts mostly red and blue color channels so it is natural to choose green as the other parameter for color balance. Increasing the value makes image greener, decreasing it makes the image more magenta.

Black Level

This setting simply subtracts a constant value to the image in linear space. The effect has major impact to contrast in the darkest parts of image but virtually no effect in midtones or highlights.

Black level 0

Black level 500

Setting black level to negative value adds a constant fog to the image. The effect is the equivalent to giving a constant exposure to the film during development process. This is called "flashing" and is usually considered an error. But sometimes it is used as an visual effect, e.g. in some movies in the 70s.

Color profile

So here we come. If you have a new ICC profile for your camera, chick at the button in the right and select that file. If You have already used the profile for some other image you can select it from the drop down list.

When you are happy with the results save the changes by pressing Apply or OK.

Adjusting Settings of Multiple Photos at Once

If you sleect multiple photos in the thumbnail pane you can adjust conversion settings for all of them simultaneously. However, you cannot preview the changes.

If some of the parameters are different initially the values for different photos are show with a blue diamond shape below the slider and the text field is grayed.