[Setup]: WizardBackImageFile

Specifies the name(s) of the image file(s) to display as the background of wizard pages in Setup, but not in Uninstall. Wildcards are supported and the files(s) must be located in your installation's source directory when running the compiler, unless a fully qualified pathname is specified or the pathname is prefixed by "compiler:", in which case it looks for the file in the compiler directory.

Supports .bmp and .png images, including those with transparency. Use WizardImageBackColor to customize the background color. Even transparent .bmp files are supported, see WizardImageAlphaFormat for more information. Use WizardBackImageOpacity to increase transparency.

The size of the area in which the image is displayed depends on the system's DPI setting and whether the default font, WizardSizePercent, and WizardKeepAspectRatio settings are being used. If WizardKeepAspectRatio is set to yes, which is the default, an aspect ratio of 497:360 is maintained. The specified image should have the same aspect ratio.

Any size of image may be used; by default, images that are too small or too large to fit in the image area will be stretched or shrunk. Specifying an image larger than 596x432 is recommended to avoid the image looking blurry on higher-DPI systems.

If a single larger-sized image does not produce a satisfactory result across different DPI settings, multiple files may be specified, separated by commas. In that case, Setup will automatically select the one that best matches the size of the image area. Assuming the default font, WizardSizePercent, and WizardKeepAspectRatio settings are being used, the size of the image area at various DPI settings is:

(You may notice that the size at 200% is not exactly double the 100% size. This is because the scaling factor is based on the dimensions of the font that a DPI setting uses, not the DPI itself.)

If this directive is set to a blank value, no background image will be used.

Otherwise, if a custom style is not specified by WizardStyle, it will automatically activate custom style windows11 with modifiers excludelightcontrols and hidebevels. Note that in light mode, the windows11 custom style uses an off-white background color. To revert this, set WizardBackColor to white.

To show only the background image and no other wizard images, set both WizardImageFile and WizardSmallImageFile to blank values. Alternatively set WizardImageOpacity to for example 150 to make both those images partially transparent.

Use support function WizardSetBackImage to set, update, or remove the background image at runtime.

; Use separate background images for light and dark appearances
WizardBackImageFile=MyBackImage.png
WizardBackImageFileDynamicDark=MyBackImage_Dark.png
; Hide the large and small wizard images
WizardImageFile=
WizardSmallImageFile=

; Use the same background image for both light and dark appearances
WizardBackImageFile=MyBackImage.png
WizardBackImageFileDynamicDark=MyBackImage.png
; Apply transparency to the background image so it works well in
; both light and dark appearances
WizardBackImageOpacity=150
; Keep large and small wizard images, applying transparency so they
; blend with the background image
WizardImageOpacity=150

; Use a background image in the wizard, and also use custom
; background colors on other windows, and in Uninstall
WizardBackImageFile=MyBackImage.png
WizardBackImageFileDynamicDark=MyBackImage.png
WizardBackColor=#ffc0cb
WizardBackColorDynamicDark=#570c22
; On wizard pages blend the background image and color together
WizardBackImageOpacity=150

See also:
WizardImageFile
WizardSmallImageFile
WizardBackColor
WizardBackImageOpacity
WizardImageAlphaFormat
WizardImageStretch