Although the newer DOCX Word format has been around since Word 2007, many people still have older DOC files laying around. Anyone that has tried saving many to the newer DOCX format has probably noticed a loss in image quality, particularly when printed.
From my own testing, I have indeed found this to be the case. In fact, choosing any ‘Do not compress …’ or ‘Preserve quality’ setting I could find had no effect. The resulting DOCX file always ended up with degraded image quality.
Occasionally I had to convert a document to be able to extract the images from, so it would be great to retain the image quality. For example, 7-zip can quickly extract the images from a DOCX file, which it cannot do with a legacy DOC file.
A demo of the image degradation
To demonstrate this issue, I created a legacy DOC (Word 97-2003) Word document containing the same diagram in three different sizes:
I then reopened the document and saved it in the modern DOCX Word format. Just before saving it, I went into the Tools menu, ‘Compress Pictures’ and deselected the ‘Delete cropped areas of pictures’ option. I also chose the ‘High fidelity: preserves quality of the original picture’ option:
Before closing the document, I zoomed to 300% and took a screenshot. I then closed and reopened the resulting DOCX document, zoomed to 300% and took another screenshot.
The following shows the two screenshots side by side of the third ‘Small’ diagram:
Besides looking grainy, the writing below the two bolts is no longer legible. For example, the ‘M4*8-14’ on the left looks like ‘N4*B-14’ on the right.
When I use ‘7-zip’ to examine the contents of the resulting DOCX file, Word clearly applied compression to the second and third images. The original diagram inserted three times was a 180KB PNG file:
How to save as DOCX, without image compression
Notice how the first image remained uncompressed above. In the past, I resized any images I was interested in to double or triple their original size before saving in the DOCX format. The problem here is that large high resolution images could not resize any larger due to the page size constraints.
In fact, the setting to maintain the image quality is obscured in plain sight in the ‘Save as’ box, at least in Word 2016. Although not obvious, this ‘Maintain compatibility’ setting preserves all images even with the lowest ’96 ppi’ setting chosen in ‘Compress images’ from my testing:
With this setting chosen, the resulting DOCX file appears quite different in 7-Zip:
With just one image file present, Word clearly used the one file for the three image sizes in the document. Even with the two larger images removed, Word does not compress the small image.
The following shows a comparison of the small diagram. This small image was clearly degraded when we converted without choosing the ‘Maintain compatibility setting’:
Finally, the following shows the resulting file sizes from our tests:
- DOC – Original Word file containing the diagram in three different sizes.
- DOCX #1 – Degraded images, despite choosing ‘High fidelity’ setting for ‘Compress pictures’.
- DOCX #2 – Image quality retained, only ‘Maintain compatibility’ setting chosen. No other setting touched.
- DOCX #3 – Image quality retained, ‘Maintain compatibility’ and ‘E-mail (96 ppi)’ chosen for ‘Compress pictures’.