Tutorial: AKVIS Enhancer

HDR Mode: High Dynamic Range Imaging

This tutorial explains how to use AKVIS Enhancer to obtain an HDR-image from a series of shots taken with different exposure settings.

• Step 1. Launch AKVIS Enhancer.

• Step 2. Open several shots of the same scene taken with different exposure settings (they must be in JPEG format). For this purpose click on and select the required files from the Open images dialog box. Under the Image Window you can see thumbnails of the opened files; and in the Image Window (Before tab) one of the opened images is shown.
  

  The check-box near the thumbnail indicates if the image will be used when generating an HDR-image. Deactivate the check-box near the image with a left-click, if you do not want to use it in creation of the HDR-image.

  Hint: Here you can learn how to get a series of shots with different exposure settings using a digital camera (click to read about bracketing).

  Attention! If the shots do not contain any exposure information you will see the Set Exposure Value dialog box where you can enter the values manually.

  At first the program calculates exposure for every shot automatically; then you can change the values either by selecting the exposure step in the drop-down menu or by entering arbitrary values.

  • The button Reset restores the automatically calculated exposure values.

  • The button Apply opens the images taking into account the set exposures.

  • The button Cancel closes the dialog box.

• Step 3. Select the value of the Preview Size parameter.

  The parameter sets the image size at the preliminary processing stage and can have the following values: 1, ½, ¼, and ¹/8. At value = 1, the size of the original image (its width and height) do not change. At value = ½, it is reduced twice, at value = ¼, it is reduced by 4 times, at value = ¹/8. – by 8 times. The processing time is reduced accordingly.

  The Preview Size parameter is an auxiliary tool, it does not influence the real size of the image. The original image will stay the same and all details of the original image will be kept.

  The parameter speeds up the pre-processing stage when one tries different settings to obtain the best result. It is useful on photos that do not require close attention to every part of it and it is enough to see the general outcome (for example, when processing photos for printing in the standard size).

  Note: Once you have adjusted the parameters, it is recommended to try the processing with Preview Size = 1 to make sure that the best settings are chosen.

• Step 4. Adjust the settings for the HDR-image in the HDR tab of the Settings panel.

  • Adjust the alignment quality of the images by selecting one of the following options: Fast alignment, Normal alignment and High-quality alignment.

    The better the alignment quality, the longer is the processing time. We recommend Normal alignment.

    If you are sure that there is no shift in the image series choose No alignment.

  • When the check-box Standard Tone Curve is enabled, the HDR-image is generated using the standard tone curve.

    Every digital camera has its own tone curve that defines the dynamic range compression. We recommend to use the Standard tone curve that suits most cameras. When the check-box Standard Tone Curve is disabled, the tone curve is calculated individually for the present series of images. It can produce an unpredictable result.

These two parameters influence the generation of an image with an expanded dynamic range (HDR image).

• Step 5. Select one of the standard presets:

  • AKVIS Natural: The resulting image looks natural and close to reality.

  • AKVIS Expressive: The resulting image is bright, high in contrast, and impressive.

  • AKVIS Default It is the golden mean between a natural image and an artistic effect that one usually wants to obtain when creating an HDR-image.

  Or adjust the Tone Mapping settings in the HDR tab and Post Processing settings yourself.

• Step 6. There are the following Tone Mapping parameters:

  • The Saturation parameter is used to change the intensity of the image colors. It accepts values between 0 and 100; the default value is 40.

  • The Lowlights parameter is used to improve the contrast of the image by increasing the minimum brightness value (black point). It accepts values between 0 and 100. As you increase the value of the parameter, the dark parts of the image get lighter and details in these areas get clearer.

  • The Highlights parameter is used to improve the contrast of the image by reducing the maximum brightness value (white point). It accepts values between 0 and 100. As you move the slider to the right, the value of the parameter increases and the light areas get darker, while the details in these parts get more distinct.

  • The Level of Detail parameter defines the amount of details detected. It accepts values between 0 and 15 with the default value of 0. As the value is increased, the color transition becomes sharper and more detail is visible. On underexposed images the high value of this parameter may cause noise.

  • The Lightness parameter is used to change of the overall lightness of the image - to make it darker or lighter. It accepts values between 0 and 100. By default it is set to 50. As you move the slider to the right, the image gets lighter; as you move the slider to the left - it gets darker.

  • The Dark Detail parameter influences the illumination of details in shadows. It accepts values between 0 and 100 with the default value of 10. As you increase the value of the parameter, the dark details get lighter.

  • The Light Detail parameter influences the illumination of details in highlights. It accepts values between 0 and 100 with the defau value of 50. As you increase the value of the parameter, the light details get even lighter.

  The original images will be combined to create a High Dynamic Range image. However, monitors have a lower dynamic range and can not render an HDR-image to the best advantage. That is why, a technology called Tone Mapping is applied for intelligent compression of the dynamic range and getting an LDR (low dynamic range) image. The resulting image contains more details.

  
• Step 7. For further image correction use the Post Processing tab.
• Step 8. If you like the new settings of the Tone Mapping and Post Processing parameters, you can save them as a preset and use them later. To save the settings, enter a name for the preset into the Presets field and press the button Save.

  Next time you launch the program, these settings will be used by default. To return to the initial settings of the program, click on Reset.

  To process the image with a certain preset, select this preset from the fall-out list. The image will be automatically processed with the preset's settings.

  To delete a preset, select it from the list and click on the button Delete.

• Step 9. Save the processed image into a file. Click on in the Control panel to open the Save As dialog box. Enter a name for the file, define its format (JPEG, TIFF, BMP or PNG) and select the destination folder.

• Step 10. It is possible to print the image.
• Step 11. Close AKVIS Enhancer by clicking on .