You can use the GIFBUILDER to overlay an image with another image using a transparency mask. You probably know PNG24. This file format supports an "alpha" channel (matte called in ImageMagick) which is another channel besides RGB and defines "how transparent" each pixel is.
The GDLib (even version 2) currently doesn't support it properly to overlay such an image over another one. The results are not very nice. But there is the possibility to use ImageMagick for this task.
In TYPO3 this is not done with a single image containing RGB and alpha channel to overlay but rather two separate images: The RGB image itself (overlay image) and 8-bit grayscale image defining the alpha-channel (Mask image).
To generate such an overlayed image with the GIFBUILDER you have to use code like the following:
lib.test = IMAGE
lib.test {
file = GIFBUILDER
file {
XY = 1024,768
format = jpg
quality = 88
10 = IMAGE
10.file = fileadmin/backimage.jpg
15 = IMAGE
15.offset = 420,18
15.file = fileadmin/overlay.png
15.mask = fileadmin/mask.png
# 15.mask = fileadmin/mask_i.png
}
}
You will need a background image. Here "backimage.jpg". For example:
Then you will need an image to overlay over the original. It should have no alpha channel. The background doesn't care when it gets masked away by the mask.
And as last thing you will need the transparency mask. It depends on your Image Magick version and setting wether the black or the white areas will be completely transparent or not. Here is an example of an image mask and inversion of it:
And here the inversed:
The resulting masked image will look like:
You can create the mask from a colored file using the ImageMagick command "-colorspace GRAY". You can negate it by adding the command "-negate". But this tasks can also be done with every better image manipulation tool (Gimp i.e.).
If your designer supplies you with a Photoshop file with transparency mask (or a PNG) you will have to extract the alpha channel information out of the image. I don't know how this works in Photoshop but I can explain the required steps for GIMP:
- Open the alpha-layer PNG
- Right click on Image (RCI) > Layer > Mask > Add Layer Mask: Select "Layer's alpha channel"
- In the Layers Dialog you see a little black/white thumb next to the Layer's thumb now. Click on the thumb of the colored image to select working on the image and not on the layer mask.
- Select everything (CTRL-A) cut everything (CTRL-K)
- Fill the image with Black or White (only the masked regions will show up colored - the alpha layer mask)
- Insert a new layer and color it opposite of the filling (black or white). Move the layer tothe correct position so it is below the just filled regions.
- Now you should have a black white image containing the mask from the alpha layer.
- You can invert the mask after you have flattened it using "Filters > Colors > Value Invert"
To extract the mask as greyscale 8-bit PNG, use the following command
convert alphaLayerPng.png -channel matte -separate +channel -negate png8:mask.png
To get the image without the alpha channel use the following command:
convert alphaLayerPng.png +matte image.png
notice - Note
Using the GIFBUILDER you can also create images from photos and insert a box which could probably be semi-transparent so the background shines through, And insert some "transparent" letters which will let the background image shine through into the box.
Here's an example. It is just done with an simple IMAGE cObject but could also get used for GMENUs for example. Then you could retrieve the background image from the media field for example.
The base image is the same as above. Below's the result - just see yourself:
lib.header = IMAGE
lib.header {
file = GIFBUILDER
file {
XY = 640,480
format = png
10 = IMAGE
10.file = fileadmin/backimage.jpg
# Example 1, Light grey box (#cccccc) no box transparency
20 = IMAGE
20 {
offset = 50,50
XY = [mask.W],40
file = GIFBUILDER
file {
XY = 400,40
# The color of the Box
backColor = #cccccc
}
mask = GIFBUILDER
mask {
XY = [10.w]+40,40
# The transparency of the box:
# #000000 = fully transparent like the text
# #ffffff = nothing transparent at all
backColor = #ffffff
10 = TEXT
10 {
text = TYPO3 rulez !
# The transparency of the text.
# Same rules as above
fontColor = #000000
fontSize = 20
offset = 20,30
fontFile = fileadmin/ALTdragon.ttf
}
}
}
# Example 2, light green box / half transparent
30 = IMAGE
30 {
offset = 50,120
XY = [mask.W],40
file = GIFBUILDER
file {
XY = 400,40
backColor = #66ff66
}
mask = GIFBUILDER
mask {
XY = [10.w]+40,40
backColor = #808080
10 = TEXT
10 {
text = TYPO3 rulez !
fontColor = #000000
fontSize = 20
offset = 20,30
fontFile = fileadmin/ALTdragon.ttf
}
}
}
# Example 2, light red box / no box transparency, bold + not antialiased text
40 = IMAGE
40 {
offset = 50,190
XY = [mask.W],40
file = GIFBUILDER
file {
XY = 400,40
backColor = #ff6666
}
mask = GIFBUILDER
mask {
XY = [10.w]+40,40
backColor = #ffffff
10 = TEXT
10 {
text = TYPO3 rulez !
fontColor = #000000
fontSize = 20
offset = 20,30
fontFile = fileadmin/ALTdragon.ttf
# Bold
iterations = 5
# Antialiased
antiAlias = 0
}
}
}
}
}
You surely once have required to have some shadows around all the images you insert as content element. This is easily possible using one of the following two TypoScript [deprecated wiki link] variants.
Here a background image gets used. The background image (shadow.png) gets scaled to the width and height of the image and the image gets put on top of it with an offset of 10,10 pixels:
# None required
tt_content.image.20.1.file >
tt_content.image.20.1.file = GIFBUILDER
tt_content.image.20.1.file {
XY = [10.w],[10.h]
10 = IMAGE
10 {
# Background image
file.import.override = fileadmin/shadow.png
file.maxW.field = imagewidth
}
# Scale background image
15 = SCALE
15.width = [10.w]
# Background Image is 20 pixel higher than scaled down "real" image
# Thus it should have "normal" height.
15.height = [20.h]+20
# Put real image on top of it
20 = IMAGE
20 {
file.import.current = 1
file.width.stdWrap = 1
file.width.stdWrap.field = imagewidth
# The real image is made 20 pixels more narrow than set in the Content element
file.width.stdWrap.wrap = |-20
file.width.prioriCalc = intval
# Inserted at offset 10,10
offset = 10,10
}
}
Here a background image with a gradient has been "underlied" under the image:
Here a dark box get's created bottom-right of the final image locations and get's blurred. This simulates a shadow. Then the image get's placed on top of it.
lib.shadowIntensity = #999999
tt_content.image.20.1.file >
tt_content.image.20.1.file = GIFBUILDER
tt_content.image.20.1.file {
XY = [10.w]+20,[10.h]+20
# The background color of the image/content
backColor = #ffffff
# Create a "dummy" image from the real image which is 20 pixel
# smaller than the set width.
10 = IMAGE
10 {
file.import.current = 1
file.width.stdWrap = 1
file.width.stdWrap.field = imagewidth
file.width.stdWrap.wrap = |-20
file.width.prioriCalc = intval
offset = 10,10
}
# Draw a black/gray box over the dummy image
20 = BOX
20.dimensions = 10,10,[10.w],[10.h]
# You have to set lib.shadowIntensity in your constants.
20.color = {$lib.shadowIntensity}
# Blur the black box
30 = EFFECT
30.value = blur=99 |
# Blur again if required (wider blurred edge/shadow)
# 31 < .30
# Put the image on top again at a slightly more left top position.
50 < .10
50.offset = 5,5
}
Notice: above code won't work inside a TemplaVoila FlexForm for various reasons (the TS parser crashes at line file.width.stdWrap.wrap = |-20 and copy instructions like 50 < .10 don't work).
The following code does work inside a TemplaVoila DS:
10 = IMAGE
10.file = GIFBUILDER
10.file {
XY = [10.w]+20,[10.h]+20
backColor = #ffffff
10 = IMAGE
10{
file.import = uploads/tx_templavoila/
file.import.current = 1
file.import.listNum = 0
file.maxW = 161
offset = 10,10
}
20 = BOX
20.dimensions = 10,10,[10.w],[10.h]
20.color = #CCCCCC
30 = EFFECT
30.value = blur=99|
40=IMAGE
40{
file.import = uploads/tx_templavoila/
file.import.current = 1
file.import.listNum = 0
file.maxW = 161
}
40.offset = 7,7
}
Here the result of the blur method. It looks quite good.
The lower method should give better results in case you do not need to blend a specific background image in.
You can Adjust the blur=99 value to lower values to get smaller blurred edges. Or you can additionally blur multiple times which will give a wider blurred/shadow area.
You can change the color set via lib.shadowIntensity Constant to lower values (more black) to get more intense shadows or to a lighter value for lighter shadows.
If you find that GIFBUILDER objects' quality is too poor for your needs, here are some suggestions made on 06.02.21 on the T3 Dev list by JoH that should enable you to create much better quality images:
- To get best results you should always set [GFX][gdlib_png]=1 in the Install Tool. Otherwise all internal operations will be done with GIF which only supports 256 colors. As soon as this option is set, all image operations are done internally with PNG images but still using 256 colors. This is due to the fact that PNG had to be used as a replacement for the patented GIF format a few years ago.
- Never use JPG or GIF as source files for the GIFBUILDER - they always contain artefacts that will be multiplied by the rendering process - use uncompressed TIF or maybe even AI files instead.
- Render the images twice the size of the original output size and then use the SCALE function in GIFBUILDER as the last object in the list to scale them down to the desired size. (Will render fonts with anti-aliasing even without the niceText property of the GIFBUILDER TEXT object enabled as a side effect).
- For T3 version lower than 4.x use the KB all colors extension which enables GIFBUILDER to render images with 24bit colors instead of 256 if you have gdlib2 available. (Will be implemented in T3 versions 4.x+)
- Starting with TYPO3 4.0 the GIFBUILDER includes the code of the kb_allcolors extension which enables TYPO3 to render full color images without the need of an extra XCLASSing extension.
- If you would also like to use truecolor PNG images by using the .format=png option in a GIFBUILDER or GMENU option, you will also have to set the newly introduced variable [GFX][png_truecolor] in the Install Tool. (But note that this will drastically increase the filesize of your images (400KB instead of 100KB and similar).
Huge thanks go to Bernhard Kraft who spent days to finally solve this problem. Great work!
On a recent Ubuntu host (gdlib > 2) I got just a couple of pixels as result of resizing transparent PNG images. The following was missing in my localconf.php to get nice images:
$TYPO3_CONF_VARS['GFX']['gdlib_2'] = '1';
(Thomas Meixner)