Mercury 100 User's Manual

Title Bar

Title Bar » Theme Image

Title Bar » Titles

Title Bar » Logo Image

Index Page & Icons

Index Page & Icons » Folder Menu

Index Page & Icons » Options

Index Page & Icons » Icons

Index Page & Icons » Icon Style


Thumbnails » Layout

Thumbnail » Captions

Thumbnails » Folders

Thumbnails » Images


Overlays » "New" Overlay

Overlays » Overlay Icons


Slides » Title & Caption

Slides » Options


Metadata » Metadata Display

Metadata » EXIF Fields

Metadata » Custom Metadata

Metadata » Metadata Sequence


Maps » Google Map

Fonts » Album

Fonts » Album » Font Family

Fonts » Album » Google Fonts

Fonts » Album » WOFF Files

Fonts » Index Page

Fonts » Index Page » Font Styles

Fonts » Thumbnails

Fonts » Thumbnails » Font Styles

Fonts » Slides & Info Page

Fonts » Slides & Info Page » Slides Font Styles

Fonts » Slides & Info Page » Info Page Font Styles


Text » Tooltips

Text » Templates

Text » "New" Overlay

Text » Maps & Metadata

Info Page » Design

Info Page » Design » Layout

Info Page » Design » Contact

Info Page » Design » Image

Info Page » Text

Info Page » Text » Title

Info Page » Text » Body

Code » CSS

Code » CSS

Code » Top & Bottom Info

Code » Top & Bottom Info

Code » Index Page

Code » Index Page » Head

Code » Index Page » Body Opening

Code » Index Page » Body Closing

Code » Slide Page

Code » Slide Page » Head

Code » Slide Page » Body Opening

Code » Slide Page » Body Closing




Custom » Create a custom style

Custom » Index & Slide Pages

Custom » Theme Image

Custom » Banner Title Bar

Custom » Folder Menu

Custom » Info Page



Image & Folder Settings

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

Then choose Edit.

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

Info: Video Support

In Mercury, 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. The slide page window that displays the video will be same size as the video's native dimensions, reduced as necessary to fit within the visitor's viewport. If those dimensions are larger than the image bounds chosen under Settings » Images » General » Image bounds » Images, the dimensions will be reduced to fit within those bounds, preserving the aspect ratio. The actual video file in the album will not be adjusted - only the player window is scaled down as necessary. If you provide the site visitor with a download icon, he will be given the video in its actual, native dimensions.

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.

Mercury can also support externally-hosted videos from YouTube and Vimeo. To use this method, see Info: Hosted Videos.

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

Mercury 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 & Folder 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 and folder 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: Google Fonts & WOFF Files

A longstanding problem with web pages is that fonts are not actually included in the page code. The page simply includes some text, along with an instruction in the CSS that tells the browser what font to use to display that text. But if the visitor's computer doesn't have that font installed, it falls back to a default, or works its way down whatever font stack is indicated in the CSS until it finds a font that it can use. The effect of this limitation is that web page designers are generally forced to rely on a small set of "web safe" fonts, fonts that can reliably be found on most visitors' computers.

Packaging fonts with web pages in a way that allows the site visitor to install the font on his computer, while possible, runs afoul of copyright protections. Most fonts, even those normally distributed with a new computer, are protected by copyright, and you don't have the right to make them available to others.

To address this problem, Google fonts and Web Open Font Format (WOFF) files can be used. The font is not actually installed on the visitor's computer. It is used only for displaying text on your web page.

In this skin, you may add two Google fonts and two WOFF files, and tell the skin which font to use for each text element, with the default being the selected regular font family. Decorative fonts can be difficult to read at smaller sizes, and are therefore best used only for page titles. You are likely to find that they look better when displayed with a larger font size than you would use for a regular font, and with normal weight, rather than bold. More traditional fonts may be suitable for all other text.

To choose a Google font, visit the Google fonts page, and identify the font you want to use. Scroll down on the page to view suggested font pairings. You might want to use a more elaborate font for titles, and a simpler font for captions. Make a note of its name, and enter the name in the skin settings. The skin does not support the use of Google font multiple styles. If you see a font listed, and it indicates that there are multiple styles of that font available, when you enter its name in the skin settings, the skin will use the basic style of that font.

There are now many hundreds of free WOFF files available. Search the web for free woff to find sources (some sites require registration). In most cases, the fonts are free for you to use on your website, even if the website is commercial, but the font designers retain copyright, so you don't have permission to redistribute the files directly to others. Often, these free fonts are provided in a variety of formats - WOFF, WOFF2, OTF, TTF, EOT, SVG, and so on. The format needed for the skin is indicated by a .woff2 (preferred) or .woff file extension. In many cases, the download will be provided as a zip archive containing several formats - you need to extract the WOFF file from that archive and use that one for inclusion in the project.

A recent judicial ruling in the EU has made the inclusion of Google fonts on a page problematic, if you are subject to EU regulations. The court found that using a Google font exposes the site visitor's IP address to Google, which violates the GDPR. This, of course, is complete nonsense, promulgated by people who don't understand how the internet works.

However, this skin copies the Google fonts you have chosen to the album during the album build, so it is bundled with the album. Your site visitors therefore never link to the Google fonts site.

Info: Included Images

Under Settings » Images » General » Include, you may choose to use Scaled images, Originals, or both.

If you choose only Originals, 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 only 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 Scaled images, videos will be shown in their native dimensions, or to fit within the image bounds, or to fit within the visitor's viewport, whichever is smaller. If you choose only Originals, videos will be shown in their native dimensions, or to fit within the visitor's viewport, whichever is smaller.

If you choose Scaled images, YouTube and Vimeo videos will be shown in the dimensions you have specified under the image and folder settings, or to fit within the image bounds, or to fit within the visitor's viewport, whichever is smaller. If you choose only Originals, YouTube and Vimeo videos will be shown in the dimensions you have specified under the image and folder settings, or to fit within the visitor's viewport, whichever is smaller.

If you choose Scaled images, PDF's will be shown in a square window that fits within the image bounds, or to fit within the visitor's viewport, whichever is smaller. If you choose only Originals, PDF's will be shown in a square window with a maximum size of 1080x1080 pixels, 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, Settings » Images » Advanced, 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. Even on a regular monitor, these thumbnails look better when hovered, since the images are expanded when the visitor mouses over them. 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: Master Album

With almost any skin, it's possible to create folders and subfolders, and produce a multilevel album. But in most cases, all levels must use the same skin, and usually the same style of that skin, as well. Mercury, however, can be used to create a master index of other albums; each album may use a different style of the Mercury skin, or a different skin entirely.

Info: Version Updating

New versions of Mercury 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

Mercury produces albums that display properly in most browsers.

Mercury License

The Mercury skin for jAlbum, including all supporting files, source code, compiled code, and scripts, ©2024, 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. Selling the software is expressly prohibited. You may modify the software for your own use.

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

For personal use, the jAlbum application requires a Standard license. For commercial use, a Pro license is required. Visit the jAlbum site for further information.