Adjust dynamic range view for hdr images, Convert from 32 bits to 8 or 16 bpc – Adobe Photoshop CS4 User Manual
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USING PHOTOSHOP CS4
Opening and importing images
Last updated 1/10/2010
If you chose to save the merged image as an 8-bits or 16-bpc image, the HDR Conversion dialog box opens. Make the
exposure and contrast corrections to produce an image with the dynamic range (tonal range) you want. For more
information, see “
Convert from 32 bits to 8 or 16 bpc
Adjust dynamic range view for HDR images
The dynamic range of HDR images exceeds the display capabilities of standard computer monitors. When you open
an HDR image in Photoshop, it can look very dark or washed out. Photoshop lets you adjust the preview so that the
monitor displays an HDR image whose highlights and shadows aren’t washed out or too dark. The preview settings
are stored in the HDR image file (PSD, PSB, and TIFF only) and are applied whenever the file is opened in Photoshop.
Preview adjustments don’t edit the HDR image file, all the HDR image information remains intact. Use the Exposure
adjustment (Image > Adjustments
> Exposure) to make exposure edits to the 32-bpc HDR image.
To view 32-bit readouts in the Info panel, click the Eyedropper icon in the Info panel and choose 32-Bit from the
pop-up menu.
1
Open a 32-bpc HDR image in Photoshop, and choose View
> 32-Bit Preview Options.
2
In the 32-bit Preview Options dialog box, choose an option from the Method menu:
Exposure And Gamma
Adjusts the brightness and contrast.
Highlight Compression
Compresses the highlight values in the HDR image so they fall within the luminance values
range of the 8- or 16-bpc image file.
3
If you chose Exposure And Gamma, move the Exposure and Gamma sliders to adjust the brightness and contrast
of the image preview.
4
Click OK.
You can also adjust the preview of an HDR image open in Photoshop by clicking the triangle in the status bar of the
document window and choosing 32-Bit Exposure from the pop-up menu. Move the slider to set the white point for
viewing the HDR image. Double-click the slider to return to the default exposure setting. Since the adjustment is made
per view, you can have the same HDR image open in multiple windows, each with a different preview adjustment.
Preview adjustments made with this method are not stored in the HDR image file.
More Help topics
Adjust Exposure for HDR images
Convert from 32 bits to 8 or 16 bpc
HDR images contain luminance levels that far exceed the luminance data that can be stored in 8- or 16-bpc image files.
You can make exposure and contrast corrections when converting a 32-bpc HDR image to 8 or 16 bpc to produce an
image with the dynamic range (tonal range) you want.
1
Open a 32-bpc image and choose Image > Mode
> 16 Bits/Channel or 8 Bits/Channel.
2
In the HDR Conversion dialog box, choose a method for adjusting the brightness and contrast in the image:
Exposure and Gamma
Lets you manually adjust the brightness and contrast of the HDR image.
Highlight Compression
Compresses the highlight values in the HDR image so they fall within the luminance values
range of the 8- or 16-bpc image file. No further adjustments are necessary; this method is automatic. Click
OK to
convert the 32-bpc image.
Equalize Histogram
Compresses the dynamic range of the HDR image while trying to preserve some contrast. No
further adjustments are necessary; this method is automatic. Click
OK to convert the 32-bpc image.