Images not appearing in chm output

Hi Peter,

I have responded to your email and I hope the information is what you requested.

In the meantime, I have also been in contact with Adobe support and we had a longer remote session yesterday without identifying and resolving the challenge. We went through relevant components to ensure there is no misalignment between component versions and did not find anything. We also reinstalled RoboHelp from scratch without success.

Since both you and Adobe have managed to compile functional versions of my RoboHelp test project using the same version of RoboHelp (2020.8.34), the conclusion is that the issue resides on my end. We have not been able to identify the root cause, but suspect it may be due to configurations imposed by corporate IT settings and policies.

I recommend that we leave this conundrum unsolved and conclude on this thread.

Thanks.

Hi Peter,

thanks for your suggestions and questions.

For the completeness of this thread:

• Yes, I can reduce the resolution. It was not intentional and had no value in itself to use a large image, I just picked a random one for testing. Reducing the resolution addresses the challenge with "Cannot open the file at mk:MSITStore..." and lets me open the generated chm, however the image still does not show.
• I have tried the Insert Image option, either by clicking the toolbar icon or using Ctrl+G, and it does not impact the outcome. Whether I download the image first and insert it using the toolbar icon, or copy-paste it straight into the editor, the two resulting images stored in the ./assets/images are identical on the byte level. Comparing the two in a HEX editor shows two identical files. It is seems as if the images are currupted when the chm output preset is generated. At least I can see that after unpacking the chm, all NUL elements in the binary image formats have been removed. NUL values are stripped from both png and jpg leading to image formats that are no longer recognized. Unfortunately, it seems as if the challenge is image formate agnostic, so there is no workaround by changing the image format.

Thanks again!

Peter,

Thanks for your quick reply.

Unfortunately, neither thread under Item 6 resolves my problem. Further, as far as I understand this, that item only relates to the "Cannot open the file at mk:MSITStore..." error message. While I thougth that piece of information might be useful, I now think it is a red herring. This error only occurs when I try to include a large high resolution image which seems to cause the compilation fails as the resulting chm file is only 1 KB.

Hence, the true challenge remains:

When I include an image from the local harddisk, it does not show when I open the generated chm output, as illustrated in Image3 and Image6.

Continued Investigation:

I have carried out some further investigations. I did prepare a zip archive with the three different tests including RoboHelp project folders and the associated chm outputs, but unfortunately zip is not an allowed file type.

1) TestProject-NoImg:

• Create new project by File > New Project
• Add a Microsoft HTML Help output preset
• Output chm file size: 47,183 bytes

2) TestProject-ImgURL:

• Create new project by File > New Project
• Add an image where the source references a URL at the bottom of First Topic
• Add a Microsoft HTML Help output preset
• Output chm file size: 47.277 bytes

3) TestProject-ImgLocal:

• Create new project by File > New Project
• Add an image where the source references a file on the local harddisk at the bottom of First Topic (Image file size: 3,734 bytes)
• Add a Microsoft HTML Help output preset
• Output chm file size: 51,439 bytes

chm outputs for all three projects are also attached.

The following is observed:

• The chm files for the first two configurations work as expected.
• The chm file for the last configuration does not show the image included
• The chm files for the first two configurations are almost similar in size as the second one only uses a URL as a reference to the image
• The chm file for the last configuration is about 4 KB larger, which corresponds to the size of the local image included.

So far, so good.

If I use 7-Zip to decompile the chm file for the last configuration, configuration 3), I get a folder structure which includes a folder assets. In turn, assets has two sub-folders: css and images. images contains a single file, image.png.

So far so good, this corresponds to the structure of the RoboHelp project.

If I try to open image.png the following message is displayed: "It appears that we don't support this file format."

Hence, image.png, as incorporated into the chm by RoboHelp has been corrputed.

The two figures below show the image properties. Comparing the two files, the original file is 3.734 bytes whereas the one extracted from the chm is 3,702 bytes, and more importantly, the latter lacks dimensions.

Investigating the two binaries in a HEX editor reveals that in the extracted, all values 00 have been removed.

The images below shows that following the default png file identifier 89 50 4E 47 0D 0A 1A 0A, the original file contains three 00 which seem to have been purged by RoboHelp. The same goes for any NUL (00) values in the png. In turn, this results in a currupt image which cannot be displayed.

I guess this explains the effect but not the cause.

Unless there are some settings I am not aware of which may address this, it seems as if I need to direct this query to Adobe rather than this forum. Nevertheless, I though I should share my findings.

original - Properties

extracted - Properties

original - HEX editor

extracted - HEX editor