GX7 image resolution

norman shearer wrote:

alcelc wrote:

norman shearer wrote:

alcelc wrote:

No, dpi (dot pre inch) or better described in digital world, ppi (pixel per inch), is something you instruct your printer to or print a hard copy of image. So, if at a printing resolution of 300 ppi, a 3000 x 3000 (9Mp image) can print out a 10" x 10" hard copy without any enlargement. Of course if you print at 100 ppi, you can get a 30" x 30" printout. When a printout of 300 ppi can look good at certain distance, at the same distance a 100 ppi print out would look less well resolved. That is the only difference between different resolution of printing.

However, it has nothing to do with the output from you camera. Of course you can capture a lower resolution image out of the camera (e.g. 3:2 mode, or S size etc). However it will just limit the headroom of how you can use the image, e.g. print large, view on a higher resolution screen, to crop etc.

Sorry to jump in but on a similar note. If I elected to use a smaller size in camera would the camera still shoot full size and then reduce it afterwards to the selected size?

If shooting RAW, for the brand I used, it must be in full resolution.

Sorry, I should've been clearer. I know about raw, it's been my mainstay since I learned about post processing. I meant smaller size jpeg.

If shooting in jpg, when a smaller than full resolution output be selected, the pixel data from a smaller section of the sensor would be recorded. Therefore, it is no difference from shooting an image in full resolution, and crop it by an editor later. IMHO its IQ including noise condition would remain the same as a full resolution output at the time of recording (providing the output will not be viewed >100%).

That doesn't quite sound right. Cropping from an editor later changes the AOV much like APS-C mode from a FF sensor camera. In which case it first takes a full resolution image and then resizes it.

For the example of a 16Mp M43 Panasonic camera, there are a few ways to produce a cropped SOOC jpg image. The most usual way, select a non native aspect ratio. At full resolution, it must be 4:3 (4592 x 3448), at 3:2, it will become 14Mp (4592 x 3064) such that the top and bottom area of the sensor would be cropped. These will not materially affect the AoV.

However, similar to the APSC crop mode of FF camera, Panasonic camera also has a so called Extended Tele Converter feature, which will give a cropping effect of max 2x. If use a 14mm M43 lens, under the effect we can get an AoV eq to 28mm of M43 but will result a 8Mp SOOC jpg. This sort of in-camera cropping will change the AoV. Under this mode, no software interpolation be made to enlarge the 8Mp output to 16Mp (Digital Zoom does it).

I guess you mean it samples fewer pixels at the time of capture.

It is very simple, just discard the data from the cropped area, and use the data from remaining area to create the file. Hence, under this mode Panasonic will produce a jpg, not raw.

If this is so then the resolution will be less.

I shall not mix the idea of picture quality usually referring to the degree of compression of a jpg by the camera, that the actual file size could be reduced for the same amount of pixels recorded. The higher compression the lower IQ from the best quality of jpg output.

Hmm. That actually sounds more like what it is doing effectively.

If not then a smaller jpeg size derived from the same size sensor may have less noise?

I'm just thinking this because I have Sony A7S and that is good for high ISO due to bigger pixels etc.

Pixel size is fixed when manufactured.

Good point. So it's omitting data somehow.

Data from certain pixels not recorded (used) will not affect the physical size of the sensor. And the total amount of light received by the sensor will also remain unchanged. So use a <100% resolution will not give any benefit except for a narrower AoV only.

AOV is unchanged though.

See above.

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