ImageMagick Examples --
Montage, Arrays of Images

Index

ImageMagick Examples Preface and Index

Montage, Introduction and General

• Geometry - Tile Size (Image Resize)
• Geometry - Tile Spacing
• Tile Layout Controls
• Frame Decoration
• Border Decoration
• Shadow Decoration
• Labeling Montage Images
• Using Saved Image MetaData
• Leaving Gaps in a Montage

Montage Settings

• Montage Color Settings
• Montage Control Settings
• Re-Using Settings for Image Read/Creation
• Montage vs Magick Option Differences

Indexes of Image Directories

• HTML Thumbnail Image Maps (basic index map)
• Smaller HTML Index Maps, using JPEG images
• Visual Index (A non-montage solution)
• A Montage of Polaroid Photos (a fancy index map)

Special Techniques in using Monatge

• Montage into Columns
• Overlapped Montage Tiles
• Montage Concatenation Mode
• Zero Geometry (caution required)
• Background and Transparency Handling

The original use of "magick montage" is to generate tables of image thumbnails, that is, to reference thumbnails of large collections of images, especially photos. And while it still can be used for that purpose, it can also do a lot more. This page examines what you can do with montage, and how you can use it on your own images.

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Montage, Introduction

The "magick montage" command is designed to produce an array of thumbnail images. Sort of like a proof sheet of a large collection of images. The default "magick montage" with no options is very plain, with quite large containment squares, no frame, labels, or shadows.

Geometry - Tile Size and Image Resizing

The "-geometry" setting, is the most important control of "magick montage". It defines the size of the individual thumbnail images, and the spacing between them. The size part of the geometry is used as an argument to the Resize Operator, including all its special purpose flags. The position part of the option is interpreted as the amount of border space to leave around the image, so making this smaller, will make the gaps between the images smaller. The default "-geometry" setting is '120x120>+4+3' which means to fit any image given into a box 120x120 pixel in size. If the image is larger shrink it, but don't resize smaller images (as per the Only Shrink Larger ('>') Flag. The 'tile' size is then set to the largest dimentions of all the resized images, and the size actually specified. That means you will never get a tile size that is smaller than the specified "-geometry" size. You can remove huge size of the tiles in the previous example space by modifing the "-geometry" default. For example by removing the 'size' component, none of the images will be resized, and the 'tile' size will be set to the largest dimensions of all the images given. For example, here I ask montage to tile using the largest image given with a small gap between tiles. This is a very typical setting to use when all the input images are small and roughly same size. For example, here I replaced one image with a larger 'logo' image, but set a the resize setting to '48x48' to resize both smaller and larger images. And here I again restrict the resize to just images larger than the specified tile size. As you can see the spacing between images appears to be larger than the requested 2 pixel spacing. But that is not the case. The tiles are still separated by 2 pixels, but the images themselves do not fill the 48x48 tile size requested. The 'logo' image was still resized to fit into the 48x48 pixel tile. If you don't want any resizing, then only define the spacing between the tiles. Alternatively, use a special size such as '1x1<' which tells IM to only resize smaller images to the given size. As no image can be smaller that 1 pixel, no image will be resized. The tile size will thus be again the largest dimention of all the images on the page. See Zero Geometry, caution required for reasons why you may like to do this.

Geometry - Tile Spacing

The positional part of the "-geometry" setting, will add space between the individual 'tiles', by adding a Border of those dimensions around the tiles before Appending them together. That means for the default "-geometry" setting, of '+4+3', the tiles will be spaced from the left and right edges of the final image by 4 pixels, and will have a 8 pixel (twice the size given) spacing horizontally between the tiles. The same goes for the vertical spacing. Note how the space bewteen the tiles when all the images were resized (second last example) is twice the size of the space around the edges.

Tile Layout Controls

The next most important option in "magick montage" is the "-tile" setting. This tells montage what limits you want on how the tiled images are to be laid out on the final result. In ImageMagick version 6 "magick montage" will make an educated guess as to how best to tile a given number of images, when you provide no "-tile" hints. It does however assume that the images being tiled are roughly squarish in nature, as it does not look at the images aspect ratios, when deciding on the tiling to use.

The strange "[1-5]" syntax is an UNIX shell shorthand, which is expanded into a list of filenames. The "magick montage" command itself does not see these characters, just the resulting list of files.

ImageMagick is pretty good at figuring out the right "-tile" setting to use for a specific number of input images. Here is a table of number of input images and the tile setting IM will used to layout those images.

Num Images Tile Setting 1 1x1 2 2x1 3 3x1 4 2x2 5 - 6 3x2 7 - 8 4x2

Num Images Tile Setting 9 3x3 10 - 12 4x3 13 - 15 5x3 16 - 20 5x4 21 - 24 6x4 25 5x5

Num Images Tile Setting 26 - 30 6x5 31 - 36 7x5 31 - 35 7x5 36 6x6 37 - 42 7x6 43 - 48 8x6

Note however that IM will not automatically select a 'perfect fit' 6x3 tile setting for 18 images, nor a 7x4 setting for 28 images. However if you specify a specific "-tile" setting, montage will always create an image big enough to hold that many 'tiles'. As you can see montage created an image that is large enough to hold the number of tiles specified, regardless of how many images are available to fill the tile space requested, be it 7 images, or just 1 image. It will only fill the space row by row, no option is currently provided to do a column-by-column fill of the tile space.

Before IM v6.1 montage would automatically truncate the extra space if the number of images did not use that space. As such a setting such as the first "9x1" image would have been truncated to produce a "7x1" tile image. Because of this, past users of montage often used large numbers such as "999x1" to generate a single row of images. Now such a argument will produce a very long image, and could take a long time for IM to complete. As such... Avoid the use of very large tile numbers in IM montage!

You can avoid the problems of extra space, and multiple images, especially for an unknown number of input images, by removing either a row, or the column number, from the "-tile" setting. The missing number will be taken by montage as being variable and montage will only create enough tile space to hold ALL the input images, producing only one image, never multiple images. This is the more typical use of the "-tile" setting, as it ensures the montage is sized correctly, while still allowing it some control in determining the final array size. Note the last image, in the above where we requested 9 columns of images. IM still generated the requested 9 columns, even though less than 9 images were given. On the other hand the first image (one row requested), is exactly the right length to hold all the images. If you have more input images than montage can tile into the space given by a "-tile" setting, then multiple images can be generated by montage, either resulting in image sequence numbers being added to the filename, or some sort of GIF animation, being created. See Writing Multiple Images for details. For example, here I have asked montage to save separate images for each page generated, by supplying a '%d' for the frame/scene/page number of each image filename.

Frame Decoration

The best part of using montage to arrange images is that it provides a lot of extra controls to add extra 'fluff' around each image. For example, you can better define the images being displayed by adding a "-frame" around each image. This is not like the same option in "magick" (See Adding a 3D frame example). The montage frame option will automatically figure out default values for the internal and external bevel of the frame. As such only a single argument number is needed.

Border Decoration

Sometime around IM v6.1.0, "-border" became a new decorative option of montage. It now adds extra 'padding' around each image, after it has been resized according ot the "-geometry" setting.

The "-border" decoration does not currently work when the Frame Decoration is also applied.

Before IM v6.1.0 (approx) -border would been applied to images at the point in which it appeared in the "magick montage" command line, just like it would have with "magick". That is, border would have been thus added to the image long before the images get resized (according to "-geometry"), which resulted in different border widths around each image depending on the size of the image at that point. It was to remove this inconsistancy that -border became a special montage setting.

Shadow Decoration

Adding a shadow with the frame is also quite good. Of course you don't actually need a frame to generate image shadows As of IM v6.3.1 when 'soft shadows' were implemented, the shadows will now be shaped according to the transparency of the images being displayed!

magick montage font_1.gif font_7.gif font_2.gif font_0.gif \ -tile x1 -shadow -geometry +3+5 -background none \ shadow_shaped.png

As you can see the shadow used by montage is actually a semi-transparent color, allowing the background to affect its final color. This means if you create a montage with textured background, or use a transparent background and overlay it, the shadow will do the right thing. Of course you need to use an image format that can handle semi-transparent colors, like PNG. Remember because of GIF Boolean Transparency you can not use GIF image file format for this purpose. Note that shadows do not care about the "-geometry" spacing between the images. As such if the images are too close together, the shadow of previous images can be obscured by later images. For example... It is thus recommended at a reasonable amount of "-geometry" spacing be provided when using shadow. To avoid 'edge clipping' shadows to much, the "-shadow" option will add 4 extra edge spacing pixels the right and bottom edges of the final image. This is on top of the normal "-geometry" spacing provided. However as you can see above, this is not always enough space. Montage currently also provides no controls for the offset, color or the 'softness' of the generated shadow (at least not yet), but then, you didn't have such control with hard rectangular shadow that was provided by older versions of montage.

Labeling Montage Images

You can also tell montage to label the image with their source filenames, though you probably need to resize the image frames, or the labels may not fit, truncating the text label. In this case we added a "60x60>" to the geometry string, which tells IM to shrink larger images to fit into this space, but not to enlarge images if they are smaller. This is probably the most typical use of montage. The '%f' is a special format character, which can pull out various details about the images in memory. See Image Property Escapes for details of other information you can extract from images. You don't have to use a "-frame" when labeling thumbnails. The labels are not shadowed, so that they remain clearly readable. And as of IM v 6.2.1 you can now re-label images after they have been read in using the "-set" image attribute operator. Lets use the "-set" operator to add more information about the images. And also few more montage settings... As we showed in the examples above you can use the "-label" setting to define the default label for an image, as they are read in, or you can re-label the image afterward using the "-set" operator.

Note that '%wx%h gives the current pixel width and height of the image as it is in memory. If the image size was modified, such as during input this may be different to the images in disk (or creation) size. Use '%[width]x%[height]' instead if you want its in memory pixel size.

You can also label images differently by setting label of individual images. Either option can be used, though you will need to use of parenthesis to limit what images the "-set" operator will be applied to. Here for example we use both forms of labeling. But lets also add a title to the montage, just because we can... You can turn off image labeling for the next image(s) by using a "-label '' " or "+label". However as you will see later these two settings are not quite the same. The same applies for a post reading, label "-set" operation. The last image shows how using a space for an image label, you can create a image label space, but leave it blank. This presents a good rule of thumb when using montage... You don't have to label your images during the montage operation itself. Both the MIFF and PNG formats, can store a label as part of their image format. Montage will automatically label any image read in that already contains a label. This is automatic and does not need to be specified, and I have used this technique to generate some very complex image montages. For example the montage array in Annotate Angle Examples was created using this technique. If you do not want this automatic labeling, you must specifically tell montage to reset all the labels being read in or created to the empty string, using "-label ''" before reading the image. Or you can just delete the label meta-data using "+set label" after reading the images. This is where "+label" differs from using an empty label ("-label ''"). The former will reset the default behavior back to automatically using any label meta-data that the image being read-in may have , while the later replaces the label with an empty string, which effectiavvly removes the label. You can also preserve the original label of the image using "-label '%l'", which can be usful as a NO-OP labeling option in image processing scripts. Note that "-set" cannot restore the original label of an image, once it has been modified or removed, either by using "-label" or "-set" In the above you can see that the first image was labeled using the label supplied with the image itself. The second had the incoming label removed by a "-label '' " setting, while the third also used the images label because we turned-off the label setting with "+label".

Using Saved Image MetaData

When generating images for later use by montage it is important to know what sort of image metadata a specific image file format can save. For example only PNG, and MIFF image file format can actually store 'label' meta-data in their saved image file format... However all the common file cormats allow you to use 'comment' meta-data, which you can use by specifying a '%c' argument to "-label". This is often more useful for pictures saved in the JPEG file format, though JPEG image comments generally are too large (often whole paragraphs describing the image), for use as montage labels, as they will not be word wrapped (see Montage of Polaroid Photos for an alternative method of labeling using image 'comment' meta-data). Many other programs also automatically add 'made-by' labels and comments to images they save (YUCK) so some caution is recommended. The GIMP program particularly likes to add such comments and labels, unless you tell it not to, every time you save an image. Note that IM is generally not used to add comments to saved JPEG files, (due to JPEG Lossy Compression) unless processing them for other reasons. Instead they are usually added by some other method in order to avoid reading and re-writing the image data and thereby degrading the JPEG image files in which you are adding comments. See lossless JPEG Processing options, for some such methods. It is also important to note that labeling (and image 'comments') is not specific to montage. Montage just makes automatic use of image labels if present. Labels and comments are attached to images, and the their specific file formats, and is not montage or even IM specific. The PNG and MIFF file format also allow you to use a less commonly used 'caption' meta-data. Actually both these file formats allow you to save ANY Image property Meta-data that may be present in an image when it is saved!

Leaving Gaps in a Montage

While you can leave extra space in a montage at the bottom by judicious use of the "-tile" setting and controlling the number of images given, leaving an empty tile space in the middle of a montage requires the use of a special image. The "null:" generated image was defined specifically for this purpose. The position in which it appears will not receive any label (even if one is defined), nor will it have any frame or shadow 'fluff' added. The tile is just left completely empty except for the background color (or texture) of the montage drawing canvas itself. Note that to other IM commands the "null:" image is represented a single pixel transparent image. It is also used as a 'error image' for options like "-crop" or "-trim" which could produce a 'zero' or empty image as a result of the operation. This special image cannot be saved and then later used to leave gaps, currently it is only 'special' if given on the command line of "magick montage".

There is no method, at this time to allow montaged images to span multiple rows or columns, as you can in HTML tables. Nor can you generate variable sized rows and columns to best fit the array of images being generated. If you really need this sort of ability you will need to develop your own montage type of application. If you do develop something, then please contribute, and we'll see about merging it into the existing montage application. Some solutions for this includes labeling and framing the image thumbnails yourself and then using either Append Images or use a more free form Layering Image technique.

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More Montage Settings

The "magick montage" settings I have shown above are only the basic controls for montage. Their are a lot of other settings you may like to consider for your own needs.

Montage Color Settings

-background	The color outside the drawn frame. Often this is set to the 'none' or 'transparent', for use on web pages. The -texture setting will be used instead if given.
-bordercolor	The fill color inside the frame for images, or any border padding. Any transparent areas in an image will become this color, unless no such decoration is added.
-mattecolor	The color used as the frame color. Note that the color is also made lighter and darker to give the frame a beveled 3D look. So this setting really defines 5 colors. (See also Framing Images)
-fill	The fill color for text labels and titles.
-stroke	The stroke color for text labels and titles.

Montage Control Settings

-tile {cols}x{rows}

The number of images across and down used to fill a single montage image. If more images were read in or created than fits in a single montage image, then multiple images will be created. (See Tile Controls above)

-title {string}

Set a title over the whole montage, using the same font (but larger) as that used to label the individual images.

-frame {width}

Create a frame around the box containing the image, using the width provided (must be at least 2, but 5 or 6 is a good value). If used any transparency in images will also become the border color.

-border {width}

Create a border around the image, using the width provided. If used any transparency in images will also become the border color.

-shadow

Generate a shadow of the frame. Note that no argument is required or expected.

-texture {filename}

Use the given texture (tiled image) for the background instead of a specific color. See the section on Background and Transparency below for more information.

-geometry {W}x{H}+{X}+{Y}

Resize images after they have all been read in before montage overlays them onto its canvas. It also defines the size and the spacing between the tiles into which the images are drawn. If no size is specified the images will not be resized.

-gravity {direction}

if the image is smaller than the frame, where in the frame is the image to be placed. By default it is centered.

Added to the above are all the font settings that the "label:" image creation operator understands (See Label Image Generator). These settings are used for the creation of labels added underneath the displayed image. These include settings such as "-font", "-pointsize" (ignored for "-title"), "-density", "-fill", "-stroke", and "-strokewidth". As long as any or all of the above setting are defined or reset, before the final 'output filename' argument, montage will use them as you have requested.

Re-Using Settings for Image Read/Creation

Note however that many of these options are also used for other purposes, in either the generation of images or during image processing. But thanks to the 'do things as you see them' command line handling on IM v6, this presents no problem to the "magick montage" command. That means you are free to use any of these option settings to read, create, or modify the images being read in, then reset those settings after all the images have been read in or created. The final setting value will be what montage will use for its final processing. This was not the case in versions of IM before version 6, in which it was generally impossible to separate image creation settings, from montage settings, without generating intermediate images (such as in the Image Labels example above). Here is a practical example of setting reuse. I wanted to make a table of some of the fonts I have been using in these example pages, then reset the settings to other values for the final processing of the images by montage.

magick montage -pointsize 24 -background Lavender \ -font Candice -label Candice label:Abc-123 \ -font Corsiva -label Corsiva label:Abc-123 \ -font SheerBeauty -label SheerBeauty label:Abc-123 \ -font Ravie -label Ravie label:Abc-123 \ -font Arial -label Arial label:Abc-123 \ -font ArialI -label ArialI label:Abc-123 \ -font ArialB -label ArialB label:Abc-123 \ -font ArialBk -label ArialBk label:Abc-123 \ -font CourierNew -label CourierNew label:Abc-123 \ -font LokiCola -label LokiCola label:Abc-123 \ -font Gecko -label Gecko label:Abc-123 \ -font Wedgie -label Wedgie label:Abc-123 \ -font WebDings -label WebDings label:Abc-123 \ -font WingDings -label WingDings label:Abc-123 \ -font WingDings2 -label WingDings2 label:Abc-123 \ -font Zymbols -label Zymbols label:Abc-123 \ \ -frame 5 -geometry +2+2 -font Arial -pointsize 12 \ -background none -bordercolor SkyBlue -mattecolor DodgerBlue \ montage_fonts.gif

magick -label %f balloon.gif medical.gif present.gif shading.gif \ -mattecolor peru -frame 10x5+3+0 miff:- |\ magick montage - -tile x1 -frame 5 -geometry '64x56+5+5>' double_frame.jpg

  magick montage -label '%t\n%[width]x%[height]' \
          -size 512x512 '../img_photos/*_orig.*[120x90]' -auto-orient \
          -geometry +5+5 -tile 5x  -frame 5  -shadow  photo_index.html

  magick montage -label '%t\n%[width]x%[height]' \
          -size 512x512 '../img_photos/*_orig.*[120x90]' -auto-orient \
          -geometry +5+5 -tile 5x  -frame 5  -shadow  photo_jpeg.html
  magick photo_jpeg.png photo_jpeg.jpg
  perl -i -lpe 's/src="photo_jpeg.png"/src="photo_jpeg.jpg"/' photo_jpeg.html
  rm -f  photo_jpeg.png  photo_jpeg_map.shtml

  magick 'vid:../img_photos/*_orig.*' vid_index.gif

  magick 'vid:../img_photos/*_orig.*' vid_index.html

  magick montage -size 256x256 '../img_photos/*_orig.*' -auto-orient \
          -auto-orient -thumbnail 128x128 \
          -set caption '%t' -bordercolor AliceBlue -background grey20 \
          +polaroid \
          +set label   -background white  -geometry +1+1  -tile 4x \
          polaroid_index.html

  magick montage -size 400x400  '../img_photos/*_orig.*' \
          -auto-orient -thumbnail 200x200 \
          -set caption '%t' -bordercolor Lavender -background grey40 \
          -pointsize 9  -density 144x144  +polaroid  -resize 50% \
          +set label   -background white  -geometry +1+1  -tile 5x \
          polaroid_index2.html

  magick montage font_*.gif  -tile 1x3  -geometry 16x16+1+1  miff:- |\
    magick montage -  -geometry +0+0 -tile 5x1  montage_columns.gif

  magick montage font_*.gif  -tile 1x3  -geometry 16x16+1+1  miff:- |\
    magick - +append montage_columns_2.gif

magick montage null: font_*.gif null: \ -tile x1 -geometry -5+2 montage_overlap.jpg

magick montage null: font_*.gif null: -background none -rotate 30 \ -background white -tile x1 -geometry -8+2 montage_rot_overlap.jpg

magick montage -size 400x400 null: ../img_photos/[a-m]*_orig.* null: \ -auto-orient -thumbnail 200x200 \ -bordercolor Lavender -background black +polaroid -resize 30% \ -gravity center -background none -extent 80x80 \ -background SkyBlue -geometry -10+2 -tile x1 polaroid_overlap.jpg

magick montage balloon.gif medical.gif present.gif shading.gif \ -mode Concatenate -tile x1 montage_cat.jpg

magick montage balloon.gif medical.gif present.gif shading.gif \ -mode Concatenate -tile 2x2 montage_array.jpg

magick montage medical.gif rose: present.gif shading.gif \ granite: balloon.gif netscape: recycle.gif \ -mode Concatenate -tile 4x montage_cat2.jpg

magick montage medical.gif rose: present.gif shading.gif \ granite: balloon.gif netscape: recycle.gif \ -mode Concatenate -tile 4x -frame 5 montage_cat3.jpg

magick montage present.gif rose: shading.gif \ -frame 5 -geometry +1+1 montage_geom_1.jpg

magick montage present.gif rose: shading.gif \ -tile x1 -frame 5 -geometry +0+0 montage_geom_0.jpg

magick montage present.gif rose: shading.gif \ -frame 5 -geometry '1x1+0+0<' montage_geom_1x1.jpg

Always set a non-zero geometry when using montage

  magick montage font_9.gif  \( recycle.gif -set label recycle \)  medical.gif \
          -tile x1  -geometry +5+5  -background lightblue   bg_lightblue.gif

  magick montage font_9.gif  \( recycle.gif -set label recycle \)  medical.gif \
          -tile x1  -geometry +5+5   -texture bg.gif      bg_texture.gif

  magick montage font_9.gif  \( recycle.gif -set label recycle \)  medical.gif \
          -tile x1  -frame 5  -geometry '40x40+5+5>' \
          -bordercolor lightblue  -texture bg.gif  bg_frame.gif

  magick montage font_1.gif  \( recycle.gif -set label recycle \)  medical.gif \
          -tile x1  -frame 1  -geometry '40x40+5+5>' \
          -bordercolor lightblue  -texture bg.gif  bg_frame_1.gif

  magick montage font_2.gif  \( recycle.gif -set label recycle \)  medical.gif \
          -tile x1  -frame 2  -geometry '40x40+5+5>' \
          -bordercolor lightblue  -texture bg.gif  bg_frame_2.gif

  magick montage font_9.gif  recycle.gif  medical.gif \
          -tile x1  -geometry +2+2  -background none   bg_none.gif

  magick montage font_9.gif  recycle.gif  medical.gif \
          -tile x1 -frame 5 -geometry '40x40+5+5>' \
          -bordercolor none  -background none    bg_framed_trans.gif

  magick montage font_9.gif  recycle.gif  medical.gif \
          -tile x1  -shadow  -geometry '40x40+5+5>' \
          -texture bg.gif  bg_shadow.gif

  magick montage font_9.gif  recycle.gif  medical.gif \
          -tile x1 -frame 5 -shadow  -geometry '40x40+5+5>' \
          -bordercolor none   -texture bg.gif  bg_shadow_framed.gif

Montage Image Output Size

The mathematics of montage is straight forward...

Basically the montage width should be....
  (geometry_size + 2*frame_size + 2*geometry_offset) * images_per_column

That is, each 'cell' of montage has a fixed sized frame and spacing (border)
added around it before the cells are appended together.

In essence the size of montage is also a multiple of the tile size, which can
make it easy to break up montage, or re-arrange the 'cells', if so desired,
as they are simple fixed sized tiles in a rectangular array.

The height is similar but with tha additional spacing needed for labels and
the optional montage title, both of which are much more difficult to
calculate, as they depend heavilly on text, font, pointsize, and density
settings.

There is also an effect of adding a shadow to the montage in this calculation,
but that appears to be a simple small fixed addition to the bototm and right
edges.  It does not appear to effect the tile size used.