jAlbum / Settings / Images

This section controls how images are generated

General

Include

Thumbnails

Usually set by the skin and may be disabled if the skin requires thumbnail images.

Scaled images

Scaled-down images (web size). If you don't want to have full sized images available on the internet choose this option.

Originals

Include original, full sized images, in your album.

Note Image effects are not applied to original images.

Which linking choice should I use?

For a discourse on what linking option is best for different situations see this forum post by jGromit

settingsImagesGeneral.png

Sets image quality and size limits for thumbnail and slide images.

The bounds fields allows you to enter custom bounds too! jAlbum will never distort the width/height ratio of your images. This means that you can safely use bounds like 1000x1000 to ensure that neither the width or height goes above 1000. A ratio like 10000x800 is commonly used to allow a mix of panoramic images and ordinary images having the same height.


Scaling method

There algorithms for scaling images are Fast, Medium and Smooth. They affect how your original images get reduced, when linking to scaled-down images, in size to meet the image bounds. The settings are a trade off between speed and creating processing artefacts, depending on the image being sampled. Advantages of each method tends to be that they preserve a specific property, like hard edges. Disadvantages are the generation of artefacts such as blocking, ringing, moire and blurring. If the images generated suffer from artefacts try another scaling method.

Fast uses nearest neighbor interpolation but can result in ‘jagged results’.

Smooth is the slowest, but will give the best result. It uses an ‘area averaging’ algorithm, or if using hardware acceleration (Settings/Images/Advanced) bilinear interpolation.

Smooth, the default setting, is recommended by jAlbum. It is very similar to Medium in quality but operates slower. If you use Medium but your images are high contrast and you are not happy with the scaled images then switch to smooth.

With smooth selected, you have access to four additional variations.

settingsImagesGeneralCustomScaling.png

Blackman-Bessel, Blackman-Sinc, Lanczos and Mitchell. These are all variations of the standard method and give greater scope for getting the best possible scaled image.


Sharpen

Sets the amount of sharpening to be applied to scaled-down images. If you are using images that are already within the image bounds then sharpening should be set to a low value. The default setting is 25.

JPEG quality

This affects the image quality and file size. A low value will result in smaller file sizes but may suffer from ‘jpeg artefacts’. A value too high will not result in a significant improvement in quality, but will result in much bigger files. The default setting is 85.

webP quality

This affects the image quality and file size. A low value will result in smaller file sizes but may suffer from ‘compression artefacts’. A value too high may not result in a significant improvement in quality, but will result in much bigger files. The default setting is 60.

Thumbnails bounds

Sets the limits for thumbnail images, width x height in pixels. Images will be scaled so that neither the width nor height exceeds the set limits.

Folders bounds

Folder image bounds needs to be supported by the skin in use. If the skin does not support them the bounds do not appear in the GUI. If supported they need to be enabled, either by the skin or the user. To enable folder images you need to check 'Process folder images', the folder images bounds then become active.

Sets the limits for folder thumbnail images, width x height in pixels. Images will be scaled so that neither the width nor height exceeds the set limits.

Images bounds

Sets the limits for scaled-down images, width x height in pixels. Images will be scaled so that neither the width nor height exceeds the set limits. This field is disabled if ‘Settings/Pages/Image linking from thumbnails’ is set to Link to originals.

The bounds fields allows you to enter custom bounds too! jAlbum will never distort the width/height ratio of your images. This means that you can safely use bounds like 1000x1000 to ensure that neither the width or height goes above 1000. A ratio like 10000x800 is commonly used to allow a mix of panoramic images and ordinary images having the same height.


HiDPI thumbnails & (slide) Images

When checked the images will be scaled to twice the size set by the image bounds, providing the original is big enough, but the album will display images as set by the image bounds. This is to support displays that have a higher pixel density than standard, for example 326 pixels per inch instead of 72ppi.

Note, if the original image is not large enough to support the HiDPI slide image size then a small yellow warning triangle will appear at the top right of the thumbnail image. There is currently no warning for thumbnail images not being big enough to generate a HiDPI thumbnail. Original images retain their size regardless of the HiDPI setting.

Variants

settingsImagesGeneralVariants.png

Variants are additional thumbnail and slide images that skins can use to serve optimally sized images for the device being used. For a mobile phone a small image will be loaded, whilst for a HD desktop a larger than the default image (image bounds) can be served. Variants are scaled images, with the scaling being a multiple of the image bounds and with scale factors between 0.25 and 4. There are presets for both thumbnails and images, they are:

Clear - remove all variants.

With JPG as the output format:

Faster - thumbnails scaled to 1, images 0.5 and 1 with webP images.

Faster and better quality - thumbnails scaled to 1 and 1.5, images by 0.5, 1 and 1.5 with webP images.

Faster and even better quality - thumbnails scaled by 1 and 2, images 0.5, 1 and 2 with webP images.

Faster and best quality - thumbnails scaled by 1 and 2 and images by 0.5, 1, 2, and 3 with webP images.

With webP as the output format:

Faster - images 0.5 with webP images.

Faster and better quality - thumbnails scaled to 1.5, images by 0.5 and 1.5 with webP images.

Faster and even better quality - thumbnails scaled by 2, images 0.5 and 2 with webP images.

Faster and best quality - thumbnails scaled by 2 and images by 0.5, 2, and 3 with webP images.


In addition to, or instead of, the preset variants you can add your own by clicking on the '+' icon. Similarly, you can remove a variant by selecting it and using the '-' icon.

You can change the image type by clicking on the 'Format' (down facing triangle) and selecting either 'webP' or 'JPEG'. WebP is an image format that generally provides smaller file sizes for the same quality as jpeg, it also preserves transparency of PNG/GIF images.


If the current skin does not support variants the settings above will be replaced by those below.
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If page linking is set to 'Link to originals' then only the thumbnail variants will be active. Any image that has been set to 'Use original' will not have slide images variants.

The bounds fields allows you to enter custom bounds too! jAlbum will never distort the width/height ratio of your images. This means that you can safely use bounds like 1000x1000 to ensure that neither the width or height goes above 1000. A ratio like 10000x800 is commonly used to allow a mix of panoramic images and ordinary images having the same height.


If HiDPI is selected then the variants will be produced at twice the shown size. For example a scale of 0.5 will actually result in a scale of 1, a scale of 1.5 will produce a scale of 3. I suggest not using HiDPI with variants.


Advanced

settingsImagesAdvanced.png

Advanced Settings controls how images are created.

Output format

The default output format for thumbnails and slides images is JPG but it can be change to webP. If webP is selected a popup warning will alert you that limitations certain browsers do not support webP yet. It may also result in more frequent remaking of images than would happen with JPG.

Note that if a skin supports webP theme images they will be remade with every ‘Make’ operation.

Lossless and transparency are both supported for webP images

Force processing of small images

Normally, if a source image is smaller than the slide image bounds, and no filters are being applied, jAlbum will copy the source file to the album but with this enabled it will process those images instead. This may be useful if your source images have lots of non repeating detail, and their file sizes are high as a result, as processing them may reduce the file size.

After enabling this to reprocess existing images you must either

Perform a 'Force Remake':
Have Preferences/Album/Synchronise output directory enabled and then exclude, re-include and 'Make album'.

Force JPEG

If selected, thumbnail and/or slide images, supported image formats will be converted to JPEG format in the album. Note, GIF thumbnail images are normally converted to PNG format but change to JPEG with this option selected. For slide images gifs are set to ‘use original’.

HiDPI thumbnails & (slide) Images

When checked the images will be scaled to twice the size set by the image bounds, providing the original is big enough, but the album will display images as set by the image bounds. This is to support displays that have a higher pixel density than standard, for example 326 pixels per inch instead of 72ppi.

Note, if the original image is not large enough to support the HiDPI slide image size then a small yellow warning triangle will appear at the top right of the thumbnail image. There is currently no warning for thumbnail images not being big enough to generate a HiDPI thumbnail. Original images retain their size regardless of the HiDPI setting.

Write webP

If selected, thumbnail and/or slide images, supported image formats will be converted to webP format in the album. If you want to ensure older browsers can display your images add a jpeg variant for both thumbnail and images.

webP images made using this option will be regenerated far more often than jpegs, only use this setting if you are happy to remake and upload unchanged images often.

Disable color subsampling

When checked and compression quality is set to 90% or more it will produce even better looking JPEGs. Disabling chroma/colour subsampling doubles the horizontal and vertical colour resolution of images, however it increases the image file size by about 17%. See this article by Rick Matthews, prefessor of physics at Wake Forest University, North Carolina.

You will need to perform a ‘Force Remake’ after toggling the ‘Disable colour subsampling’ status to have images reprocessed. To only have thumbnails without colour subsampling, tick ‘Disable colour subsampling’ AND ‘Save thumbnails with high JPEG compression quality.’

Note, images must be larger than the image bounds in general settings above.

Attempt to use hardware accelerated scaling

Will try to use graphic processors to speed up image processing. Image quality may be affected with certain graphic cards.

Superimpose play icon onto video thumbnails

If selected the ubiquitous 'play' icon, of a triangle within a circle, is superimposed on video thumbnails. Note, some skins may override this setting and apply their own custom filmstrip regardless of the setting. If the project settings was saved with this off and you turn it on and after a ‘Make album’ the overlay does not appear then a ‘Force Remake’ will be needed to force a rebuild of all images. Note, the overlay is applied only on jpg thumbnails, not webp.

Copy originals if needed

If one of the link to originals settings above is selected then checking this will add a full size copy of the original file to the album, and links to the originals point to those copies. If any originals are being used in the album and this option is not selected then broken links could appear unless the 'true' originals are accessible from the album’s location. For example the local album might work but if uploaded to the web the originals will not be accessible. It may also need to be set if linking is not to originals but some originals are included within the album.

The default is, and it is always safer to have, Copy originals if needed checked. Only uncheck this if you fully understand how linking works and you have arranged for all originals used to be accessible from the published album.

Background color for transparent images

ColorPicker.png

If force jpeg writing (above) is enabled then images with transparent backgrounds will have a background color as set here. You can open up a color picker window, see figure to the left, by double clicking on the small square just before the color value field.

Copyright embedding

You can embed XMP metadata to the generated slide images in your album. You can add creator, copyright, and a copyright URL. For this to take effect you also need to ensure Settings/Advanced/Metadata/ Include xmp metadata in generated images is checked. The metadata tags added are of the form:

Creator » xmp.dc:creator[1]
Copyright » xmp.dc:rights[1]
Copyright URL » xmp.xmpRights:WebStatement

If the information entered is changed for any reason you will need to perform a 'Force Remake' operation in order for the updated metadata to be applied. If you select 'overwrite existing,' it will replace the metadata rather than appending it.