Adding Auto Contrast makes rendering time go up 4 times

gosfordparkgosfordpark Website User Posts: 3

Dear fellow filmmakers and support team,


I m doing an old fashioned slide show in 4k. 38 min runtime. Rendering time: 2 h.... fine

Now I added Auto Contrast to all Photos and rendering time is now 8 h...  Seriously??

Did I do something wrong? I m very new to this software, may be I miss something.


Will it help to copy all photos on same SSD as Hitfilm?

Or may be I should add contrast to all photos before importing them to hitfilm....?

Anyway, tips will be gratefully appreciated. :)


My specs are i7 6700k, Geforce 1080Ti, 32 GB RAM

Kind regards



  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,226 Ambassador

    One thing about Hitfilm (and all NLEs) is they are 1) expecting VIDEO, i.e. The image to change on most frames,  2) "brute force" in that each frame is rendered as a separate image. 3) (when applicable) rendering layers in sequence.

    Auto Contrast, therefore, calculates each and every frame, which means it has to analyze every frame. That's the slowdown. 

    Either apply individual Brightness/Contrast effects to each clip in Hitfilm, or process your images before import to Hitfilm. Either way works. 

  • gosfordparkgosfordpark Website User Posts: 3

    Thanks so much, however, as English is  not my native language, I want to make sure I understand what you mean

    "Either apply individual Brightness/Contrast effects to each clip in Hitfilm"

    Does that mean I shoud render the slideshow "normally" (without the Auto-Contrast-Effect) and then reimport the file into Hitfilm and add Auto-Contrast? If not, then I would kindly ask for explanation:)




  • gosfordparkgosfordpark Website User Posts: 3

    Is there a way to select all clips and change the brightness/contrast setting altogether in one step?

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