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I don't know if i'm doing something wrong or this is the way my camera (550d/t2i) works.

It seems to me that the video is softer than it should be.

To test this I made a picture and video using the same settings (iso, f-stop, shutter speed and picture style) at the same distance and without moving the focus.

I cropped and resized the picture to match the resolution of the video (1920x1088) and then I compared the results.

Detail from movie frame

Detail from movie frame

Detail from picture (appropriately scaled)

Detail from picture (appropriately scaled)

here is an archive of the originals 550dTest.zip

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1 Answer 1

up vote 5 down vote accepted

The sensor in your camera has about 18 megapixels, and all those MP are used to record pictures and movies. What's different is how the sensor data was processed on the picture and the movie.

Scaling

For the picture you scaled down the original 18MP picture using Photoshop, GIMP or similar. This was probably a high quality scaling operation, so the resulting 2MP image still looks pretty good, since it was generated from the whole 18MP of data.

For the movie, it is the camera that did the scale down operation. The camera has to scale down images at a rate of 24 per second, so it can't use as good scaling as you get from an image editing app. I'm not sure what the algorithm is, but I'm certain its main goal is performance and not quality.

Compression

For the image you took a raw or a lightly compressed jpeg (not sure which one you used). If you went with the jpeg, it's got 4.7MB worth of data. The raw is way more than that.

For the movie the camera compressed all the frames using H.264 encoding and you took a random frame from the middle of the movie. Your movie has 58 frames and is 20.3MB big, so on average, there are just 360KB for each frame if we consider the audio and metadata in the noise. H.264 makes an amazingly efficient use of the limited bitrate by encoding differences between frames, so it isn't as bad as it looks.

So based on the above reasons, I think the picture vs. movie quality cannot be expected to match.

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