Shade 9 Save PSD
Save PSD Overview
The Save PSD function saves Shade rendered images (or Z-depth) as Adobe Photoshop (PSD format) files.
Colors are normally handled as 24-bit data (8 bits for each RGB channel). When you correct colors in Adobe Photoshop using such data, some corrections may cause problems, such as “tone jumps” due to the lack of color depth.
If you make color corrections using 48-bit color data (16 bits per channel) and later drop it down to 24-bit color data, the tone jumps are smoother, even if the color corrections were extreme.
Allowing you to save images with 16 bits per channel, the PSD 16bpc serves as an essential tool for professionals and artists who require delicate control over color.
Each of the RGB channels, and the Alpha channel, in a normal rendered image is displayed and saved using 8 bits per channel. We therefore refer to these images as 24-bit (or 32-bit if the Alpha channel is included).
If the Real Color option in the Shade Rendering Options is turned on, you can keep the full 96-bit data (32 bits for each RGB channel) computed by the Shade Renderer. Usually, the 96-bit data is rounded off to 24-bit data to be displayed and saved.
The Save PSD function accesses the 96-bit data before it’s rounded off, and uses this data to save 48-bit files (16 bits for each RGB channel), which Adobe Photoshop can handle. As for the Alpha channel, its original 8-bit depth is extended without change to 16 bits.
Therefore, you need to obtain the real colors from the rendering in order to save RGB channel data in PSD format, to take advantage of the 16 bit data.
When you apply filters and effects using Z-depth data in Photoshop, you can correct colors using Tone Curves when necessary. This may cause some problems, including “tone jumps,” when 8-bit grayscale Z-depth data is used. The 16-bit gray-scale Zdepth data significantly reduces these problems.
If the Keep Z option in the Shade Rendering Options is turned on, you can keep the full 32-bit Z-depth data computed by the Shade Renderer.
The Save PSD function rounds off the 32-bit Zdepth data and saves it as a 16-bit gray-scale Adobe Photoshop file.
TIP: The “ExtractZ” plug-in bundled with Shade generates 8-bit Z-depth data. For details on the “ExtractZ” plugin, refer to the “ExtractZ” description in the Effectors section of this plug-in manual. You therefore need to set the rendering options to keep Z-depth values if you want to save the Z-depth data in 16-bit PSD format.
Handling 16-Bit Data Files
Manipulating 16-bit data in Adobe Photoshop has considerable limitations, as compared with the manipulation of normal 8-bit data. For details, see the Adobe Photoshop manuals.
Using the Save PSD Plug-in
Before saving in PSD format, you should check the settings in the Misc. tab of the Rendering Options.
To save RGB data as 16bit/channel PSD, turn on the Real Color check box, then render. Similarly, to save Z-depth data in PSD, turn on the Keep Z check box before rendering.
The save options vary according to whether Z-depth or real color data was maintained.
TIP: If the image does not have any Z-depth values, you can not save the gray-scale Z-depth data in PSD format. If the image does not have any real color data, you can save the color data as a PSD file, but can not take advantage of the 16 bit data.
Note: Rendering with the Real Color or Keep Z check box on uses more memory than it does with them off. In particular, be careful when rendering elaborate shape data or high-resolution images.
Saving a PSD File
Below is the procedure used to save a rendered image with the Save PSD function.
1. Press the Save button in the Image window (or select Save from the contextual menu of the Image window) to display the Save As dialog box. Select Photoshop (*psd) from the File type pull-down menu and press the Save button.
Note: You can also save an image in PSD format from windows other than the Image window, in which case the image is saved using 8-bits/channel and you can not save the Z-depth values. Animations can be saved in PSD format in the same way as rendered images.
2. The Save PSD format image dialog box is displayed.
This figure shows the save options dialog box for an image rendered with both the Real Color and Keep Z check boxes turned on.
For more details on these settings, refer to the Save PSD function Reference section below.
3. Specify your settings and click the OK button to save the image.
Opening a File Saved with the Save PSD Function
After opening a file saved with the Save PSD function using Adobe Photoshop, select the Mode submenu in the Image menu in Adobe Photoshop and make sure that “16 Bits/Channel” has a check mark.
Note: We have confirmed that a 16-bit PSD file saved with the Save PSD function can be properly opened in Adobe Photoshop 3.0 and later versions.
Save PSD Reference
Save PSD Format Image Dialog
The upper figure shows the Save PSD format image dialog box for an image without real color data and Z-depth data. The lower figure shows that for an image with both of them.
This dialog box shows different optional items depending on the image being saved: items related to RGB channels and the Alpha channel when the image has real color data; and those related to gray-scale Zdepth data when the image has Z-depth data.
The type and channel architecture of an exported Adobe Photoshop file vary with the combination of RGB channels, Alpha channel, and gray-scale Z-depth information selected here.
The table above shows the results for the various combinations of check boxes.
Color Depth Pull-down Menu
Select the color depth for saving the image. Your choice may be only 8bit/ch, or may include 8bit/ ch and 16bit/ch, depending on whether or not you maintained the real color data and Z-depth data in the rendered image.
Save RGB Channels Check Box
The RGB channel data is saved when this check box is on. If 16bit/ch is selected for the color depth, you need to specify the highlight level in the lower 16bit/ ch Options.
Process Mode Pull-down Menu
You can specify the processing speed for saving the RGB channels here. Fast processing uses more memory.
These options are shown only when the image has real color data. They are only effective when 16bit/ ch is selected for the color depth and the Save RGB channels check box is on.
Keep Highlight Pull-down Menu
Real color data maintains higher tone level than the highest level in the normal color data (which is white). The image areas with such values higher than white are referred to as “Ultra Highlight” areas. The setting here represents to what extent such values of real color data should be maintained with the saved image.
This setting affects the tone of RGB channels for the saved image. Off
To convert the data to 48-bit, the plug-in clips the highlight area of the data according to the view in the Shade Image window. The image is therefore saved with the same tone as the rendered image in the Shade Image window.
On (Auto Clip Level)
This option does not clip the ultra highlight area, maintains the full tone of the real color data, and converts the whole tone range to 48-bit and saves it so that it falls within the normal gradation range.
Since the highest value of the real color data becomes the highest tone level (white) for the saved image, this option typically produces a darker image.
On (Manual Clip Level)
This option controls the tone of the highlight areas using numeric input.
The value defined in the White Clip Level text box is applied as the highest tone level (white) for the saved image.
White Clip Level Text Box
Entry to this text box is effective only when ON (Manual Clip Level) is selected in the Keep highlight pull-down menu. Enter the value to apply as the highest tone level (white) for the saved image. All tone levels above this value in the real color data will be clipped (cut off).
- When you choose ON (Auto Clip Level) or ON (Manual Clip Level) in the Keep highlight pull-down menu and click the OK button, a dialog box appears to show the “Default Hightlight Level.” (This message is not displayed when saving an animation.)
If you enter this Default Hightlight Level value into the far-right Input Levels text box in the Photoshop Levels adjustment window and click OK, the image in Photoshop will be adjusted to be as close as possible to the image saved with OFF selected in the Keep highlight pull-down menu.
Levels adjustment window in Adobe Photoshop
If you want to control the color tone of the highlight areas in Adobe Photoshop, the Default Highlight Level shown here will serve as a reference.
Save Alpha Channel Check Box
The Alpha channel data is saved when this check box is on.
Save Grayscaled Z-depth Check Box
This check box is displayed only when the image includes Z-depth data.
When this check box is on, gray scale Z-depth data is saved.
Within the rendered scene, the object closest to the camera is displayed as black while the object farthest from the camera is displayed as white. The gray value for the background area without any object (where the Alpha-channel value is 0) is unknown.