The Image Options form can be accessed from all file selection forms when saving images to disk.
Different sections of the form will be enabled depending on which file format is being used and the supported features.
If an image which is currently part of an Impact project (either as a 2D graphic or a 3D texture) is being saved then no changes in size can be done. For these images the Image Size and Physical Size sections will be inactive on the form but the Image Properties can be altered. The physical size of the image will be set to the default value of 72 dpi. This is because any changes made by the user to the image size would alter its resolution in pixels.
If the Send To > Graphics File tool is being used and the form is opened it will allow the image's resolution and physical size to be edited along with any compression and encoding options.
Generally, if the image is being created while saving then image size and resolution can be edited. If the image already exists in Impact then it's saved at its current size and a default 72 dpi resolution.
Image Size
Width
Enter the width of the image in pixels.
Height
Enter the height of the image in pixels.
Lock Aspect Ratio
Switch this option on to link the Width and Height controls together. When this is done, altering one entry field will automatically alter the other to ensure the ratio between them is kept the same.
Physical Size
Here you can set the width and height of the image in distance measurements.
The Lock Aspect Ratio option also applies to these values.
Choose your required units from:
- Millimetres
- Centimetres
- Inches
Resolution
Use this option to set the density of pixels over a certain physical distance and therefore the resolution.
The units of the resolution value can also be chosen from:
- Pixels / Millimetre
- Pixels / Centimetre
- Pixels / Inch
The units of the width and height values are kept independent from the resolution units because most people prefer to work with Pixels / Inch, but people may be measuring physical size in metric units.
Editing Resolution Controls
If the Lock Aspect Ratio checkbox is selected then the ratio between the width and height in pixels and the physical width and height will be maintained.
The relationship between the width and height in pixels as defined in the Image Size section and the physical width and height is as follows:
Width in Pixels = Physical Width * Resolution
Height in Pixels = Physical Height * Resolution
If the value of the width or height in pixels is changed then the physical width and height will also be updated to maintain the Resolution value.
If the value of either the physical width or height is changed then the width and height in pixels will also be updated to maintain the Resolution value.
If the Resolution value is changed then the width and height in pixels will be updated to maintain the relationship with the physical width and height.
Image Properties
This section displays different options depending on the file format being saved. In general these will usually include the Colour Depth and some adjustments for compression. However certain file formats may allow other important options to be adjusted and these will be included here.
Colour Depth
Select the image colour depth from the following:
- 16 Million Colours (32 bit)
- 16 Million Colours (24 bit)
- 256 Colours (8 bit)
- Greyscale (8 bit)
- 16 Colours (4 bit)
- 2 Colours (1 bit)
These choices depend on the selected file format and will be omitted from the list if not supported.
The Compressed, Uncompressed and LZW compression options allow different compression types for certain formats including TIFF.
The Standard, Progressive and Lossless options are relevant for JPEG file compression.
The Compression Factor can be adjusted by entering an integer value directly or by dragging the slider. These two values are connected and if one is changed the other updates.
Background
Colour
Use the colour picker to define the background colour for the exported file. This will always default to the project's current background colour. However, you can still add custom colours in the colour selection form.
Background colour control is only relevant for 2D layer image capture, and will not affect 3D layer output. Instead, consider using the 'Transparent Background' option within the 3D Snapshot Tool and 3D Snapshot Settings
Ok
Select this option to close the form and return to the file selection form. The options will then be used as parameters to the graphics library if the file is saved. The settings will also be saved to the current user's settings file so that they will be remembered.
Cancel
Select this option to close the form and return to the file selection form. In this case the changed options will not be updated.