June 24, 2009

K-7 as a movie camera -- PART III: Sample video

-> Link to part I

After all the preparation, I would like to share a short and uninspired video with you. And some thoughts about post processing ...

This is a short video sequence shot at 1536 x 1024 with a Pentax K-7 during an oldtimer car meeting earlier this year near Munich.

Pentax K-7 movie in 1080p from falconeye on Vimeo.

This video is nothing special. But I will use it to illustrate

Options for post-processing

1. The form factor.

720p video is 1280x720, 1080p video is 1920x1080, both in 16:9 aspect ratio. The native video capture is in 1536x1024 or 3:2 aspect ratio.

  • 1536x1024 -> 720p: magnify by 83.33%, crop 8.00% from upper and lower edge each.

  • 1536x1024 -> 1080p: magnify by 125%, crop 7.81% (100px) from upper and lower edge each.

There is no benefit in recording in 720p directly, except for a better control of framing (16:9 framing on rear display) and smaller file sizes. For 720p, the camera does the same supersampling to 83% size one would do in post-processing otherwise. On the other side, keeping the 1536x1024 material provides some more options for post-processing.

1536x1024 material is not suitable for direct presentation. Here, 720p is a better option.

2. Recoding.

Most video editing software will directly open the AVI file stored on SD card. Additionally, Apple Quicktime will open the file and Quicktime Pro allows to extract individual or all frames as images. Or to recode the movie, e.g., to MP4 AVC H.264.

Photoshop CS3/CS4 can open the AVI file directly as well and you get a video layer. There, you can do many image operations like you do for still images and recode, e.g., again to MP4.

After touching up the raw material, I used Adobe Premiere Elements for more video-oriented editing. On the Apple, MacOSX has something similiar on board, called iMovie.

3. Quality.

The K-7 captures stunning video quality. But it isn't good enough to justify the extra size coming with 1080p, compared to 720p. At least not without further touching up the quality.

Below, you'll see two frame images from the short clip above. The first is as out of the camera.

The second image is post-processed using my K-7 video IQ master (a program which I developed to defeat the "768-aliasing artifact"). The K-7 video IQ master is work in progress and yet unpublished. The basic idea is to use the insight about the submatrix as described in part I and try to correct some of the weaknesses in the original algorithm as built into the camera.

You may have to click onto the images to see the original size to study the difference. According to several opinions, the filtered footage has less fringing and less jaggy lines while still gaining (or at least maintaining) on overall detail (read: without becoming softer). It was used to create the 1080p clip in the opening of the article.

I hope that a forthcoming version of the K-7 video IQ master will be good enough to render 1080p footage to the same stunning quality we now see in 720p footage. And further improve on 720p quality. Btw, I very much welcome any comments on this topic.

As a side note. It is no problem to add motion blur to frames belonging to a panning action. Or tilt to remove the skew. Just open the corresponding video sequence in CS3.


This shall conclude my three part article about the video capabilities of the Pentax K-7.

The video mode in the Pentax K-7 looks like a very promising proposition. It can produce stunning video quality, esp. in 720p. However, Pentax made a number of trade-offs to keep the camera affordable as a still camera (and it is a high spec camera already w/o video). Therefore, to achieve maximum possible quality in movies, a number of tweaks applied during capture and in post-processing are of help.

Enjoy your moving images :)

Further reading:


  1. Falk, your K-7 video IQ master does a much better job than the K-7 engine. flipping between the two sample pics it is clear your reprocessing has improved the IQ.

  2. talk to Pentax and see if you can get paid for your video IQ master XD

  3. I am indeed looking for ways to justify investing more time into this. Suggestions welcome :)

  4. Falk, great work regarding all this low-level (meaning: dug deep) image processing stuff! Let's hope Pentax do their homework and provide much superior video and LV in their K-7.2 - maybe they could hire someone external as an advisor (hint, hint).

    I do have a niggle with the image quality of the IQ Master though: Reds develop heavy artifacts (best seen in the rightmost tractor's wheel, but also on the other tractor and on the caps of the boys at the left side). It also appears to lighten the image quite a bit.

  5. Falk, anything new with your video fix software?

  6. @Anonymous, video fix software: Thanxs for the interest. This is work in progress. As usual with software, it is more work than anticipated. I guess otherwise, many software projects would never be started ;) I am now planning towards a end of Q1 2010 release.

  7. Thanks, could you let us know about your progress on the usual websites (Cinema5D, DVXUser, DVInfo, etc). I'd hate to miss the latest on your work. There seems to be very few people writing in-depth about Pentax video. I'm a long time Pentax user and very much looking forward to seeing what next year's video-capable Pentax SLRs will be like. If they still have the same downscale issues as with the K-7, your software fix will be as essential as it is now for K-7 users!

  8. Falk, brilliant info & research in these three articles. I am reading in anticipation of getting the K-7. Also looking forward to your software as any improvements are always welcome.

  9. Hello!
    I just bought a K-7 and have been experimenting with shooting video on it. I'm much more used to my Panasonic HMC-150, but the K-7 seems intriguing.
    I have several questions:

    1. The video shot by my friend on his Canon 7D seems much more vibrant and beautiful than the video I shot on my K-7 with the kit lens.

    2. I want to use some video shot on the Pentax K-7 together with video shot on my Panasonic HMC-150 (1920x1080).
    Should I shoot at 1536x1024 instead of 1080x720 and then crop the footage to get a better image? Or would it be simply better and less troublesome to shoot in 1080x720 and upconvert if necessary?

    I would greatly appreciate some advice. Thanks!

  10. @Ray:

    1. This is most likely due to different image and color profile settings. The image and color profile settings apply to the video mode as well. You may want to experiment with the settings until you get the rendition you like best. Note that this includes shadow and highlight treatment.

    2. It somewhat depends on the scaler used. I'd shoot at 1536x1024, and crop and scale (in one step) to 1920x1080 using Squared 5's great "MPEG Streamclip" freeware. I wouldn't select too much sharpness in the camera image setting though as subsampling artifacts are much more visible at 1536x1024.

    Some downscale to 720p first, then upscale to 1080p to get rid of them. This applies to other cameras as well of course. If you do this and because K-7 creates the 720p footage by downscaling the 1536x1024p feed internally itself, you may as well shoot in 720p and have the correct aspect ration for image composition on the rear LCD. YMMV

  11. Hello!
    Thanks for your reply!
    I'm very new to all this, and so thank you for your advice. I have several other questions:
    1. Do you have any recommendations on settings for video to obtain a) punchy strong and vibrant video b) a more film-like look

    2. I'm running Linux but finding it difficult to accomplish many video-processing tasks. I'll search for MPEG Streamclip and see if it runs in WINE, and if not, I'll install a Windows partition.

    3. Why would one shoot at 1536x1024p then downsize to 720 first then upscale it again to 1080? Does this not degrade the image even more? Why not just shoot at 720?

    Thanks for your advice!

  12. @Ray:

    First of all, I think you deserve better support than the blog comment function can provide. I propose you create an account and ask questions 1 and 2 in the video subforum at . I'll try to help you there as well. I'm sure there are native Streamclip alternatives for Linux, like Avidemux. But I'm not the expert to answer this.

    Wrt question 3.: The K-7 shoots at 1536x1024p then downsizes to 720p internally if you select 720p quality. So, there is at least a theoretical chance to beat the K-7 at its internal downsampling. But if you're very new to all this as you say, just shoot 720p and upscale to 1080p to merge with 1080p content.


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