Diffs between convert.exe under ImageMagick 6 and 7

[ahauerwas]

I use ImageMagick "convert.exe" to convert a .BMP to .JPG using the command-line, and am finding significant differences between v6 and v7 both in terms of converted file size and software dependencies.

Platforms: ImageMagick convert.exe v6.7.8-2 and v7.0.5-3 Q16

Code: Select all

convert -quality 100 backgroundDefault.bmp backgroundDefault.jpg

Source: 8101 KB
v6 JPG: 227 KB
v7 JPG: 6076 KB

Forgive my ignorance, but do I need to provide additional parameters to get the file size down and get a comparable size to what I got with v6?

Also: under v6 the only dependency for convert.exe was to potentially have vcomp100.dll in the same directory, for a total of about 5MB of executables; now it seems as if multiple CORE_RL dll's are required to be in the same directory for it to run, though the total size of the files is still around 5MB. Correct?

[snibgo]

Without seeing your image files, we can only guess. V6.7.8-2 is very old, and the operation of "-quality" may have changed since then. Perhaps lowering the quality number will do what you want.

The size of executables, DLLs etc is heavily dependant on the build of IM, especially what internal delegates are included.

[fmw42]

IM 6 installs default without HDRI. IM 7 defafaults with HDRI. IM 6 compare does not use alpha. IM 7 compare includes alpha.

[ahauerwas]

Okay, have gone back to ImageMagick 6.9.8-2's convert.exe and am seeing the same behavior re: DLL dependencies and file size. I have to assume the meaning of -quality changed between 6.7.8-2 and 6.9.8-2.

The BMP is simple -- text on a single color background. I am not enough of an image professional (or an ImageMagick professional), though, to know what additional switches I should provide to the convert.exe command in order to compress this as flat as possible. I have tried all increments of the -quality switch to no avail.

I need the resulting JPG to be less than 256K, and the convert.exe command that I was using with 6.7.8-2 was doing that. Any suggestions?

Thanks for any and all guidance.

Adam

[fmw42]

Post an example BMP input and your different output JPGs. Also not that formally -quality should come after reading the input image and just before writing the JPG. IM 7 is more strict about syntax. So try

Code: Select all

convert backgroundDefault.bmp -quality 100 backgroundDefault.jpg

[snibgo]

The BMP is simple -- text on a single color background.

Why do you want JPG output? For graphics (solid colours), PNG compression is more effective.

If it really has to be JPEG, try "define jpeg:extent=XXX", eg:

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convert in.bmp jpeg:extent=256KB out.jpg