ZEN NDI® Drag&Drop Image Viewer

ReadMe File

1) General features & FAQs for all ZEN NDI® utilities

Usage Notes

2) Image files can be drag-&-dropped onto the preview window to output them as an NDI® source, with an optional background. The NDI® resolution is independent of the image size, and is set via a drop-down menu button, along with the NDI® framerate. Supported image formats include bmp, gif, png & tif file formats, at up to 32bit/pixel (i.e. including alpha/transparency).

3) By default, the output will be in RGBA mode (RGB + alpha/transparency), so that any embedded alpha information in the image files is transmitted over NDI®. If alpha information is not required (e.g. to send to a BirdDog NDI® Decoder – one with firmware that doesn’t accept RGBA format), there is a “No alpha output” option in the system menu (Rt click – top left).

4) Different scaling modes are available. Images are centred on the output and maintain their original aspect ratio in all modes.
a) “None” will use the source image with 1:1 pixel sizing (i.e. no scaling). Images will have a border (i.e not fill the screen) or be cropped to fit, depending on the relative size of the image and the chosen NDI® output resolution.
b) “Contain” will scale the image with the aim of filling the screen, but without cropping, therefore leaving borders if the aspect ration doesn’t match.
c) “Crop & Fill” will scale the image to fill the screen so that no borders remain. Parts of the source image will be cropped if the aspect ratio doesn’t match the output.

5) Different background options are available, which will appear when the source image doesn’t fill the screen. The options are selected from the menu button on the top right.
a) “Black” is a solid black background.
b) “Graduated Fill” uses two colours, which can be changed via the colour buttons below the Background menu button, and includes 3 patterns, each with the ability to quickly swap the colours via the respective “reversed” option.
c) “Copy from grabbed” enables any image to be grabbed and used as a background. Drag and drop a suitable image in the usual way, then press the “Grab” button (which will change to show “Grabbed” when active), and then select the “Copy from grabbed” menu item to create a new background. Note that the background can include transparency – the grab function will take whatever is currently on the output.
d) “None” is a transparent background.

6) The Cut/Fade transition button (lower left) selects between a straight cut and a short crossfade when a new image is loaded.

7) The Watch/Watching button enables a “watch” on the last loaded image file and, when active (green) will reload it if the file is updated.

8) The 0-255 / 16-235 button is for selecting source quantization level. Selecting 16-235 will convert the image to 0-255 using a simple 8-bit LUT (and therefore increase the contrast whilst clipping blacks below 16 and whites above 235).

9) The current config/settings can be saved and loaded at start-up, using several options in the system menu (right-click top left). Included in v1.1.x onwards.
a) When “Use Last” is enabled, the various settings (eg Resolution, Framerate, Background, Cut/fade, etc) will be saved on exit to the “last.ziv” file. This file will be loaded on start-up, if it exists, and if the “Use Last” setting had been applied, then the saved settings will be applied to the new session. When starting additional instances of the Image Viewer (eg. No 2, No 3, etc), the files are named “last2.ziv”, “last3.ziv”, etc, so that different configs can be loaded and saved for each instance.

b) When “Use Image” is also enabled, the file path to the currently loaded image will also be saved in the “last.ziv” file, and will be reloaded (after a short delay) if it can be found when the file is reloaded at the start of a new session.

/force_last Command Line

c) There is also a Command Line option that can be used, “/force_last“, which will attempt to use the settings in the “last.ziv” file, even if the Use Last setting is not enabled in the file (which would normally result in it being ignored). The purpose of this option is to create a way to ensure that a particular configuration is always loaded on start-up, irrespective of how (most of) the settings are changed during the session. To create a suitable “last.ziv” config file, apply the settings you require, but ensure “Use Last” is disabled, and then use the “Save config now” menu option to create a config file which, under normal circumstances, will be ignored, but will be forced to load (and the settings used) by the “/force_last” command line switch. Unless the “Use Last” menu option is re-enabled again, no new file will be saved on exit, so the same config will be loaded each time

10) By default, the app window has the “Always on top” attribute set, but this can be changed in the system menu, right click top left.

11) Multiple instances of the Image Viewer can be run, and each will have auto-numbered NDI® source names. Note: it is important to leave a gap of at least 3 seconds between running each instance, to allow the “instance detection” process to complete, otherwise you might be attempting to create multiple instances all with the same NDI® source name.


There is a support/discussion User Group page on Facebook – “ZEN’s Software Apps & Utilities for NDI” – just agree to the rules to join.

Version History

v1.0.0.1 12-Jan-2019 Initial release as an image viewer generating an NDI® output.

v1.0.0.2 20-Jan-2019 Added a simple “Watch” function (polled every 3 secs)

v1.0.1.3 8-Mar-1019 Added a “No alpha output” menu option

v1.0.2.4 21-Aug-2019 Recompiled with NDI® v4.0 SDK – no other changes

v1.0.2.5 6-Oct-2019 Added 0-255 / 16-235 button for selecting source quantization level

v1.0.3.6 2-Feb-2020 Added 1080×1920 “vertical HD video” resolution and recompiled with the v4.15 SDK. 32 & 64 bit versions included.

v1.0.3.7 27-Sep-2020 Recompiled to extend expiry date and use the v4.53 DLL.

v1.1.0.10 18-Mar-2021 Added “Use Last” & “Use Image” menu options for saving/loading config files. Also added F1 & system menu methods of accessing the ReadMe online, and sponsor ads at start-up. Includes the NDI® v4.62 DLL.

v1.1.0.11 30-Oct-2021 Recompiled to extend expiry date and use the NDI v5.03 DLL. 64-bit only (no 32-bit version in this release).

v1.1.0.12 5-Sep-2022 Recompiled to extend expiry date and use the NDI v5.5 DLL. 64-bit only.

v1.1.0.13 12-Jun-2023 Maintenance release, includes revised expiry warning dialog and extended lifetime.

Martin Kay
ZEN Computer Services

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