Resolution measurements - TZ30 (ZS20) - Many images

Started Apr 3, 2013 | Discussions thread
Ianperegian Veteran Member • Posts: 3,584
Re: Resolution measurements - TZ30 (ZS20) - For kkardster

Hi Jimmy,

Thanks for a very interesting thread, and thanks also for making your resolution charts freely available for people to use for their own testing.  i think your charts are very ingenious, and they provide a much more reliable way of visually assessing resolution than do the B&W "narrowing lines" charts that are often used on the review sites, as well as allowing different colours to be assessed at the same time.

I noticed kkardster's comment about the lower resolution of the yellow Es.  I wondered whether changing the background colour would have any effect, since I understand that in the demosaicing of a Bayer matrix the colour value of a pixel includes interpolation from the surrounding pixels.

I thought to try blue as the background since as you said, yellow is made up of red and green, and pure blue lacks both red and green.  I prepared a copy of your earlier Es chart with a blue background using PSE with the paint bucket tool (obviously the blue Es disappear).  Printing this chart at the correct size (75mm for the black line) with my Epson printer gave good resolution of the smallest Es, as shown in a closeup shot I took with my ZS20:

I attached the blue background chart print onto the chart board I'd previously prepared for testing my FZ38 and ZS20, as shown here .

I tested using my ZS20 at 51mm FL with the tripod adjusted to the correct distance so that the black line on the chart covered 400 pixels. Below is the resulting full sized image:

This is a 100% crop of the blue background chart beside the white background chart:

As can be seen, the blue background has had a marked influence on the Es, with the yellow Es being much better resolved, while black Es (and text) are poorly resolved.  It seems to indicate that yellow, cyan and probably other colours too, give better resolution when they are surrounded by particular other colours.  Also, I think the intensity of the background colour and the exposure would have some effect as well.

A conclusion could be that when taking shots of canaries, choose a blue sky background rather than a white clouds background!


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