First let's cover the simple case of an image that is in the template and will therefore be in the report. If we have an image that is 1" wide in the template, then it should be 1" wide in the report.
Please note that the picture here, which is a sample that comes with Windows XP, defaults to the full width of the page. But I resized it to be 1" across. The size of this picture is not set by the number of pixels in the image, it is set solely by the display width set by word. And the output will match this size.
The first difficulty comes when creating html output. There is no way in html to set the width of an image in inches. You can only set the width in pixels. So for an html report we need to set the width to the number of pixels that is 1" wide. To do this we need to know the number of Dots Per Inch (DPI) on the display device. For a monitor this is problematic because the Mac is 72 DPI, most Windows monitors are 96 or 105 DPI, and many new monitors are much higher. And then printers are anything from 300 – 2400 DPI.
We use 96 DPI but this can be overridden in the Windward properties file with "default.image.dpi=96" where you set the value you want to use. Whatever value you set, this is the width='96' value that will be used in html output for a 1" wide image.
And we now have the above image, regardless of the number of pixels that are actually in the image, taking the same space on the page in html output as it does in the template, assuming the DPI setting matches the screen it is displayed on.
Now it gets a bit more complicated. When you are inserting a bitmap using a tag, we don't have a set size in Word. Well, actually optionally we do. On both tags, for a bitmap, you can set
<wr:out select='/root/logo' width='1440' height='1080'/>
When you explicitly set the width & height that is the same as setting it in Word. So in this case you will get a 1" wide image in all output except html and you will get a 96 pixel (or whatever override setting you selected) wide image in html.
Please note, the width & height are set in twips which are twentieths of a point. As there are 72 points in an inch, there are 72 * 20 = 1440 twips in an inch.
However, if you do not set the height & width, then Windward needs to determine the size of the image. Some bitmaps have a DPI setting for that bitmap as part of the file – but only some and for those, not always. For the common formats: BMP/DIB (can but usually don't), GIF (no), JPG (yes), & PNG (almost always). You can find this setting viewing the file in a paint program but… most paint programs, if there is no DPI setting, will display a setting of 72 or 96. So if you see a value of 72 or 96, it is probably a file with no DPI setting – but probably, not definitely. The high-end paint programs like PhotoShop can tell you if it is actually set.
If a bitmap has no DPI setting, we return to our good friend 96 DPI, or the value you changed this to with default.image.dpi. So inside the Windward engine every bitmap has a DPI. It's the value in the bitmap if set and 96 (or what you use) if not. But we have a DPI.
As an aside here, a bitmap has no "natural size" based on the number of pixels in it. The size of a bitmap is always the number of pixels times the DPI. A paint program will display an image using 1 pixel on the screen for each pixel in the image, but that is not it's "correct" size and depending on the DPI setting, may be much large or smaller than it's actual size.
So when we import an image via the import or out tag, we take the width of the image in pixels, divide it by the DPI, and that is the width of the image in the created report. So to list some examples:
What can trip people up is they see the bitmap in a paint program and say it should be that wide in the report. That approach doesn't work because that display in the paint program is totally dependent on the DPI of your monitor. So the width on your screen in the paint program can be quite different from the width on my computer system. This is why we must use the DPI setting with the pixel width.
We now come to the final point, html reports once again. After we go through the above process to determine the width of the image, we return to our friend 96 DPI (or default.image.dpi) and use that DPI to determine the width= setting for the image in the html, jast as we do for an image embedded in the template as we discussed at the start.