Atom 26 User's Manual


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Image-Specific Settings

To access image-specific settings, hover on a thumbnail in the main jAlbum editing window, and click More.

Then choose Edit.

Then choose the Atom panel on the right side of the editing window.

Info: Video Support

In Atom, support for videos added to a project is dependent upon the video support built into jAlbum. For videos to work properly in an album, video support must be enabled in jAlbum under Tools (jAlbum in macOS), Preferences, Advanced.

If the processed video dimensions are larger than the image bounds chosen under Album » Settings » Images » Image bounds » Images, the display will be reduced to fit within those bounds and within the browser window, whichever is smaller. If you choose Link to originals for the project, or Use original for one video, the video will be shown in its native size, reduced as necessary to fit within the browser window. The actual video file in the album will not be adjusted - only the display window is scaled down as necessary.

With video support enabled in jAlbum, the core program automatically provides a thumbnail image for the video. In image editing mode, a slider is available to choose a video frame other than the one automatically selected. This can be especially helpful if the video starts with several seconds of a black screen - the automatically-selected frame might be black in that case.

It is possible to provide your own representing image for the video, which could be an image that doesn't even appear in the video. Choose a full-sized image (a regular JPG file, and not just a small thumbnail), change its extension to .thm, and give it the same name as your video. For example, for a video called mydog.mp4, the image file should be named mydog.thm. This file should then be added to the project at the same time the video is added to the project. This image will then be used both for the thumbnail and for the video frame while the video is loading and after it has finished playing.

Your web host must provide video files with the correct header information. The MIME type must be video/mp4 - if an MP4 file is delivered by your web host with any other MIME type, playback will fail in some browsers. If you find that a video in your album plays properly when you preview the album locally, but displays only an error message when viewed from your web host, an incorrect MIME type is the most likely cause. Ideally, your web host should correct the server configuration, but if you can change your own .htaccess file on the server, adding this line will correct the problem:

AddType video/mp4 .mp4

In addition, video files must not be compressed by the server using something like gzip, for example.

Info: Hosted Videos

Atom supports the display of videos hosted on YouTube or Vimeo.

jAlbum does not have a way of extracting a still image from an externally-hosted video to use to create a thumbnail for it. You can use a video editing program to extract a single frame, take a screenshot, or choose any other still image to represent the video in the album. This should be a full-sized JPG image, rather than a thumbnail.

Add the image file that represents the video to the project.

Because the video must be connected to a single image, you cannot use album-level settings. You must choose the settings for this video under Image-Specific Settings. jAlbum cannot determine the dimensions of an externally-hosted video, so these values should be entered manually. Enter the absolute URL for the video.

For a YouTube video, view the video on the YouTube site, click the Share button, and copy the URL that is displayed. Then click the Embed button, and make note of the width and height of the video. If there is no Embed option, that means that the person who posted the video does not allow it to be embedded on any other site, and you will not be able to use it in your album. The skin will accept either of the following URL formats:

The skin will still recognize the following formats, but these should not be used going forward. Support for them is not guaranteed, particularly the first format, which is for the obsolete YouTube Flash player:

For a Vimeo video, view the video on the Vimeo site, and click the Share button, and copy the URL that is displayed. Then click the Embed box, and make note of the width and height of the video. If you see a warning about domain restrictions on embedding, that means that the person who posted the video does not allow it to be embedded on any other site, and you will not be able to use it in your album. The skin will accept either of the following URL formats:

Enter the dimensions for the video in the image-specific settings. You can display the video larger or smaller than its native dimensions, but you should preserve the aspect ratio. If you don't, the video will be displayed with colored bars above and below the video, or on its sides.

Info: HTML Tags and jAlbum Variables

HTML tags and jAlbum variables may be used in a number of different contexts, and will be honored in the album (including things like links). jAlbum variables will be passed to the jAlbum engine and will be evaluated before they are placed in the completed album. Almost all user entries are treated in this manner:

If you use a < or > character in a text string, it is assumed to be part of an HTML tag, and may produce errors if it isn't. If you want to use one of those characters as simple text, use its HTML entity code, instead.

Info: Linking to Originals

If you choose Link to originals in the main jAlbum settings (Album » Settings » Pages), your images will not be scaled or modified in any way. They will be used directly in the slide pages of the album. The skin will adjust the slide display to the visitor's viewport, but because the files have not been scaled, the file sizes may be very large, making this setting a poor choice for a web album. However, you can resize your images before using them in jAlbum, in which case choosing Link to originals might be suitable. If you also select HiDPI images, your original images will be shown at one-half their native dimensions, to preserve clarity on high-density displays.

If you choose Link to originals, videos will be shown in their native dimensions, or to fit within the visitor's viewport, whichever is smaller.

Info: HiDPI Images

High-density display devices, like Apple's retina displays, have twice the number of physical pixels (or more) within a given area, compared to regular devices. Images will appear sharper on these displays if they are larger, but displayed in half the CSS layout space. For example, an image that is 1200px wide is normally displayed in 1200 CSS pixels on a regular monitor, and is using 1200 physical pixels. But for a high-density device, it is better to provide an image that is 2400px wide, but then display it in 1200 CSS pixels on the monitor. When you do this, the display makes full use of the 2400 pixels that are available in the image, by using 2400 of its physical pixels.

jAlbum includes the option, under Settings » Images » General, of creating high-density thumbnails and/or slide images, referred to as HiDPI images. This doesn't actually produce images with a higher pixel density - there is no such thing. It simply produces images with double the image bounds - the skin, however, then displays these images in half the space.

Doing this may produce a better-looking image on a high-density monitor. The penalty is that the image files are typically several times the file size. They consume more bandwidth, taking longer to upload and longer to download when someone visits the site. The user with a regular monitor is forced to download much larger files, but gets no benefit from them.

The skin defaults to using HiDPI thumbnails, which produces better-looking thumbnails on high-density displays. For thumbnails, this does produce larger files, but they're still relatively small, so the bandwidth penalty is minor.

Using HiDPI images is a different matter entirely. The bandwidth penalty is substantial, but the perceived improvement in display quality is not as dramatic as it is with small images like thumbnails. As the bandwidth available to your site visitors continues to grow, the greater use of bandwidth will become irrelevant. In addition, the skin does a lot of image preloading, so as a visitor moves through the slides, there will often be no delay, even with HiDPI images. Improving technology will eventually make this a non-issue, and you will be able to use HiDPI images in all your albums.

It should be noted that if the images you are adding to your project aren't fairly large to begin with, perhaps 3000x2000 pixels, there is no benefit to be gained by using HiDPI images, and there is no reason to choose that option. jAlbum can't interpolate, and produce more image information than what is present in the original images.

Recent jAlbum versions include the ability to produce albums with two sets of images, but the image display script used in this skin is not constructed to make use of them. In addition, a "2X variant" image in jAlbum is not handled the same way as a HiDPI image - the benefit of the greater density is lost.

If you want to provide HiDPI images to visitors with high-density monitors, but not penalize visitors with regular monitors, the only solution is to produce two copies of the album. Create your project and call it, for example, mydogLR (for "low resolution"), using image bounds that produce good-looking slides on a regular monitor (the skin defaults, for example). Accept the default settings - HiDPI thumbnails, but not HiDPI images. Upload your album to

Now duplicate the entire project - click the down-arrow to the right of the project name in the jAlbum project panel, choose Duplicate Project, and call it mydogHR (for "high resolution"). In this duplicate project, choose HiDPI images, make the album, and upload it to

Now you need to provide a steering script on your site, so that visitors will be directed to the appropriate album. Create a directory on your site called and upload an index.html to it that contains the following:

<!DOCTYPE html>
<meta charset='UTF-8'>
if(screen.width >= 768 && screen.height >= 768 && window.devicePixelRatio >= 2) {
	window.location = "";
} else {
	window.location = "";

All visitors can now be provided with a single link to your album: The steering script will automatically direct visitors to the high resolution album if they are on anything the size of an iPad or larger, and have a high-density display. These are the visitors who can benefit from the larger slide images. Other visitors will be directed to the low resolution album.

Info: Version Updating

New versions of Atom are published with some regularity. These new versions generally include new features, improvements, and bug fixes. The jAlbum application will let you know when a new version is available, and users are encouraged to download and install the new version.

Info: Browser Support

Atom produces albums that display properly in most browsers.

Atom License

The Atom skin for jAlbum, including all supporting files, source code, compiled code, and scripts, ©2022, Jeff Tucker.

The skin uses the following open-source scripts:

You may use the software to create albums for personal or commercial sites. You may distribute copies of the software to others, but for any reuse or distribution, you must make clear to others the license terms of this software. You may modify the software for your own use.

The copyright holder reserves the right to waive or to withdraw any of these terms on a case-by-case basis.

The jAlbum application is free for personal use during the initial trial period, but after that, a Standard license is required. For commercial use, a Pro license is required. Visit the jAlbum site for further information.