5 Replies Latest reply on Apr 16, 2008 5:11 PM by Gravenstein

    Why Save Images as .bmp?

    hughbetcha Level 1
      Just looking at all my project folders, we have hundreds and hundreds of screen captures that are .bmp format.

      I did my own test saving the same screen capture in different formats - .bmp, .jpg, and .gif.
      Results: .bmp is 955 KB, .jpg is 76 KB, and .gif is only 18 KB.

      With all these images being published to our server, I was thinking it must be important to optimize images or else I would think this could affect how quickly the pages load once online.

      As a general rule, shouldn't all the screen captures be saved as .gif? If so, why is the default for RoboScreenCapture set to save as Windows Bitmap?

        • 1. Re: Why Save Images as .bmp?
          Peter Grainge Adobe Community Professional (Moderator)
          Slowing down the loading is the reason to avoid BMPs but you need to consider your users. If they are all in one or a few locations with good download speeds and the screens load OK for them, then you could save yourself a lot of work. If they might be using a dial-up connection, then you should consider this problem.

          As to JPG/GIF, I guess you are thinking GIF is smallest so best? In terms of download speed that is true but in terms of quality JPGs have more colours so can be better. Use whatever gives you the quality you need. JPGs are still small enough in file size to be OK.

          RSC does not default to BMP. Go to Capture | Capture Settings | Quick Save. Do you have Automatically Save turned on and is that set to BMP? If not, I cannot see a setting but maybe if you start saving as JPG or GIF it will remember. Not sure but I do know it does not offer BMP as the default when I save.

          • 2. Re: Why Save Images as .bmp?
            RoboColum(n) Level 5
            Peter is right. Once you define the image format in RSC it remembers that the next time you capture.
            • 3. Re: Why Save Images as .bmp?
              Philip Tory Level 1
              Graphics Tips for browser-based Help Guides.

              For any web-based application, whether web sites or Help projects, try to minimise file sizes for quick download speeds, and optimising image sizes can make a significant differnce. for screen shotes, I strongly recommend kind of graphics package to reduce the number of colours. I use Paint Shop Pro, but there are many others on the market. (Sorry, MS Paint doesn't do what you need.)

              Which Image Format?

              These cause HUGE file sizes, and you should never need to use them. I just took a simple 980x530 screenshot of some text in MS Notepad, and this created a 1.5 Mb file, compared with 114 Kb for JPG and 28Kb for a GIF. ('Nuff said?)

              For screen shot images, diagrams or line drawings, use GIF format. This works best where there are areas of solid colour and sudden changes of colour where you have lines, boxes and text superimposed upon it.
              The GIF format is limited to 256 colours, so you will need to reduce the number of colours in your favourite graphics package. Reduce colours using the 'Nearest Colour' method; do not use 'Error Diffusion', which makes a larger file size. The result is a clear image and compact file size. Where possible, reduce the number of colours as far as you can, consistent with retaining good appearance. If you can reduce an image as far as 16 colour GIF, this will give you the smallest file size.
              DON'T use GIF for photographs because of the bands of colour that show across the photo, which it tries to fit into a 256 colour palette.

              JPG is optimised for photographs, where there are gradual changes in shade and colour.
              DON'T use JPG for screen shots because you end up with a larger file size and a 'gritty' appearance, as JPG tries to resolve the suddent transition between background white and solid black for text, for example. (See file sizes of example above).

              NEVER use PNG format in RoboHelp because it makes RH unstable and cause crashes. Trust me, I know: it has cost me many man-days downtime over the years, caused by restarting from crashes and tracking this bug down.

              TIP for smaller screen shot file sizes

              In Windows XP, switch off the default "smooth edges of screen fonts" feature, as follows.

              1. Desktop > right-click > select Properties.
              2. Select the Appearance tab, and click on the Effects button.
              3. Clear the checkbox "Use the followng method to smooth edges of screen fonts".

              Depending on the screen shot, you can save up to 40% of a finished GIF file size.

              Hope this is useful!

              Best wishes.
              • 4. Re: Why Save Images as .bmp?
                Pet3689 Level 1
                We have switched from huge BMP images (default for WinHelp I believe) to GIF to (relatively) tiny PNG. As long as we stay away from really advanced PNG features, we are fine. No RH-6/7-HTML crashes whatsoever. We did notice, however, that if we compress the PNG images with a fancy compressor tool, then RH (and HTMLHelp) cannot display them properly.

                I guess that the underlying problem is that PNG has so many fancy options which GIF does not, and RH apparently cannot handle them all.

                We did go about this carefully, however: We used a free batch conversion tool to convert BMP -> GIF -> PNG. We then used batch-search/replace to modify the file name extensions. We kept a copy of the original BMP/GIF images, just in case. But we can easily go back with the same procedure.

                However, we are very happy with the small PNG images (and 50% compressed JPG for photographs).

                I would not advise RH users NEVER to use PNG, but to use PNG with caution.
                • 5. Re: Why Save Images as .bmp?
                  Gravenstein Level 2
                  Authorgraphic, can you tell me what kind of gif would be most likely to benefit from clearing the font-smoothing setting? En masse, our graphics do take up a lot of space, so I'm interested in this. However, when I did a quick check, I didn't see very much difference between the two. There was a little, but not very much. So where would I be most likely to see a big size reduction from changing this setting?