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Creating Screenshots

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Stephen Illingworth edited this page Jun 4, 2025 · 11 revisions

Gopher2600 provides three screenshot modes. Each mode is best suited to a different type of display "kernel", although you can choose to use any mode with any type of ROM.

Hotkeys

Screenshotting is available when in play mode. It is not available in debugger mode.

  • F12 is used to save a single frame screenshot

  • Shift-F12 will cause a double frame screenshot to be saved

  • Ctrl-F12 will create a triple frame screenshot

Methods

To view the following example images at a larger size, right-click on the image and select "Open In New Tab"

Single Frame

The first of the three modes is the single frame screenshot. As the name suggests, this is an image created from a single frame of emulation. The two examples below are all of the game Pitfall. The first without CRT effects enabled and the second with effects enabled

This third image is with effects enabled and with the TV bevel enabled.

Double Frame

The double frame screenshot method is good for ROMs that use a flicker kernel. In a flicker kernel, the TV image quickly alternates between two images to create the impression of a single image. This can create an effective game display but it also means that special care is required when taking screenshots.

The images below are from the game Zookeeper by Champ Games. This game relies almost exclusively on a flicker kernel and so use of the double frame method is essential to get good results. A screenshot created with the single frame method would produce relatively poor results for this game.

Triple Frame

The triple frame method is useful for the very few games that use a three-frame flicker kernel. For example, the ChronoColour display method invented by Andrew Davie, can be captured effectively by the triple frame method.

The images below are from CDFJ version of Boulderdash, created by Davie.

Using the Wrong Method

Using the single frame method on a flicker kernel can produce disappointing results. To illustrate the importance of using the "correct" method, the two images below are of Zookeeper and Boulderdash created with the single frame method.

You can also mistakenly create a double or triple frame screenshot for a game that does not use flicker kernel. This isn't always a bad thing however. Indeed, in many instances you probably won't notice any difference. But for games with a lot of movement a triple frame capture can produce noticeable differences.

The two images below demonstrate the difference in the case of the game Wabbit. The first image was created with the single frame method and the second image was created by the triple frame method.

Filenames

Screenshot filenames will include whether the name of the ROM file (without extension), the date/time (to make the filename unique) and the screenshot method.

Some examples:

  • scrshot_Pitfall_20250604_142634_single.jpg
  • scrshot_zookeeper_20200308_demo2_NTSC_20250604_143331_double.jpg
  • scrshot_Wabbit_20250604_143419_triple.jpg

Image Dimensions

The dimensions of the saved image will be the same as the emulator window.

Limitations

The Screenshot facility is currently only available when Gopher2600 is compiled with the OpenGL 3.2 renderer.

To help make sure the quality of the screenshot is good, the amount of RF Noise is reduced to zero for the duration of the screenshotting process. You may therefore see the TV image change slightly during that brief period. Similarly, the play screen overlay is also omitted from screenshots.

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