Question on Image Parameters

[Tony_photoplus]

The website I do editorials for had a question and I wasn't aware of such a beast, but I thought that the brains in this forum would have something to say. The question was:

I am looking for some program that show me image quality parameters. I would like to compare the same images made by different cameras.

I am sure there are several ways that image breakdowns are generated (if thats the right word) and analysed. Loads of things go through my mind when I start thinking of 'Parameters'.

Tony

[Tamlin]

The first question I'd ask would be: What the hell are "image quality parameters"?
In and of itself, this phrase is meaningless, since there are many different dimensions of "image quality". Are we talking physical, technical, aesthetic or what?

This is an old (but still valid) article about digital camera image quality that might give you some idea of the depth of this subject:
http://www.luminous-landscape.com/tutorials/dq.shtml

These may also provide some pointers:
http://www.dpreview.com/learn/?/key=Pixel_Quality
http://www.dpreview.com/learn/?/Glos...c_range_01.htm
http://www.dpreview.com/learn/?/Glos...urement_01.htm

[Tony_photoplus]

Originally Posted by tamlin

The first question I'd ask would be: What the hell are "image quality parameters"?

Exactly my point I had put to the person and they hadn't gotten back to me. There are so many variables so I thought it a good debate here in BioRUST. Thanks for your input Tamlin and the links. The other question how many cameras does this person have access to?

Tony

[Tony_photoplus]

I have told the person to join the forum and put their question here should be interesting

Tony

[synthetic]

PS CS3 has some analyzing features that I have never really dug into or messed with. I wonder if this could be what is being asked for?

I am also inclined to think they are maybe seeking the lines of resolution of an image such as what I see mentioned in photo magazines reviews when they review a new camera?

[Tamlin]

Originally Posted by synthetic

PS CS3 has some analyzing features that I have never really dug into or messed with.

Really? Where are they?

Originally Posted by synthetic

I am also inclined to think they are maybe seeking the lines of resolution of an image such as what I see mentioned in photo magazines reviews when they review a new camera?

That's what I thought, too, but I have the feeling that the person asking the question thinks that there is some sort of "magic bullet" software solution - whereas those reviews are carried out by humans who (for the most part) really know what to look for and what they're talking about.

[Tony_photoplus]

Here is what I had back from that person, but I did say to come here and discuss it.

I will explain with more detail. I made some photos with one camera and two different lens. Resolution of photos is 640 x 480. I would like to know which photo I can get more information. I am making some experiments in fluid mechanical field (jets) so I would like to know which lens is the best for me. If I can get a lot of information of photo it is better for me. I don't know exactly what is important for me (histogram, etc...). Do you know some good photographic forum ?

Silly asking do I know of a good forum. No not really

Tony

[Tamlin]

OK, well I would say that if you're using the same camera, then (broadly speaking) you'll get the same "information" in both images - although it all depends (as I mentioned earlier) what you mean by "information".
If the image settings in the camera don't change (i.e. both images are the same file type and quality), then the pixel count, for example, will be exactly the same. However, if one image is shot in bright sunlight and the other indoors by artificial light, the histograms will be completely different.
There is no "easy" answer to this.

[Tony_photoplus]

Lens's are are major factor here more than camera. The thing is that they should do a test of the lens and thats the easy part. I am sure there is a lens test chart you can download, print off and do a visual assessment as a starter. One doesn't come to mind at the moment

Tony

[Tamlin]

Even just comparing lenses is a minefield. What do you need to compare? Distortions? Resolution? Vignetting? Chromatic Aberrations? Aperture range? Zoom range (if relevant)? Image stabilization (if relevant)?

Etc. etc. etc.....

[Tony_photoplus]

Maybe this will do

JimDoty.com - USAF 1951 Chart

I remember using this 1971. Oops to many years ago

Tony

[synthetic]

Originally Posted by tamlin

Really? Where are they?

nope... I was wrong. I got home at lunch and checked it out (only have CS at work). The analysis menu option at top was what I was referring to... but apparently this is for measurement of dimensions only I think... one of those things I have never used and wasn't sure what it was... I was mistaken

[supertackyman]

I would almost be inclined to suggest that if "more information" is needed that he should start with a switch to a higher resolution camera.

given that he is studying some sort of jet (water or otherwise) i would think that a higher resolution would allow for more detailed scrutiny of the fluid and its dynamics. if thats what he is trying to achieve, at 640 x 480 I dont think different lenses will cause that much change (unless one is VASTLY superior to the other. and then the choice would be pretty obvious)

the distortion of a wider anglelens will be more pronounced because you are packing more field of view onto the same amount of pixels, eventually resulting in blurry edges. and lost detail. where as a closeup lens (macro) would be putting less field of view onto the same amount of pixels producing a sharper image of a smaller area.

thats just how im thinkin'
(please feel free to correct any falsitudes I have spoken)

[synthetic]

I agree with STM... 640x480 really isn't the kind of image I would be getting really critical about unless that is the max size of a monitor they are using in the field etc.

[Tamlin]

Well, 640 x 480 = 0.3 megapixels

Even a phone camera can do better than that!