GX7 image resolution

Should I be able to set my GX7 to produce images with a 300dpi resolution? The camera is new to me and I'm still not completely familiar with all the menu options. I've searched but can't find any indication of any such option.
Help would be appreciated - either that or perhaps an explanation as to why it can't be done.

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.

wyeman wrote:

Thank you Adielle and Alcelc, that clears things up very well.

Question: If I print an image which is initially 75ppi and I change it to 300ppi in my image editing software, how does the software decide what the additional pixels will look like?

Usually it will simply interpolate the inbetween pixel.

Bass
If things appear to good to be true - they're usually neither of both.

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 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.

I could test for myself but I'd probably draw the wrong conclusions! I usually shoot RAW btw.

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.

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%).

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.

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. 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.

Some models might use a binding pixels method to avoid AoV cropping on video and it can benefit IQ. But generally on still shooting this binding method will not be applied.

I could test for myself but I'd probably draw the wrong conclusions! I usually shoot RAW btw.

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wyeman wrote:

Should I be able to set my GX7 to produce images with a 300dpi resolution? The camera is new to me and I'm still not completely familiar with all the menu options. I've searched but can't find any indication of any such option.
Help would be appreciated - either that or perhaps an explanation as to why it can't be done.

Your camera will produce files with a certain number of pixels, depending on your setting (0000 x 0000). At that stage forget DPI.

When you come to reproduce the image, you can think about DPI (more properly Pixels Per Inch, PPI, although that is a bit pedantic).  If you have an image 3000 pixels across, a reproduction 10 inches across will be 300 DPI. If you reproduce it at 1 inch across, the resolution will be 3000 DPI. At 30 inches across, it will be 100 DPI. Your printer software will probably resample the image so you can't see individual pixels even at low resolution - it just look a bit soft. In my experience, anything at 240 DPI and above looks fine, and from a reasonable viewing distance even 180 DPI can look very good. Assuming you don't resample the original file in your computer, the DPI will depend on the size at which you reproduce or view the image.  (A figure of 72 dpi sometimes comes up in file data - ignore it: it's just a placeholder.)

dinoSnake wrote:

timo wrote:

Assuming you don't resample the original file in your computer, the DPI will depend on the size at which you reproduce or view the image. (A figure of 72 dpi sometimes comes up in file data - ignore it: it's just a placeholder.)

Well, strictly speaking, 72 DPI isn't a placeholder: 72 DPI it was the standard DPI for analog CRT shadow masks, and therefore for decades was the default for anything that displayed data on that CRT - images or text, editors or viewers.

The theory of operation was that, if your CRT shadow mask was of "standard" design, you had 72DPI; and if we set our software to display/work with 72DPI as default, you got WYSIWYG (or as close as you could manage it back then).

And the de facto 'standard' stuck. And hung around, even beyond 72DPI displays to, now, 144+ DPI displays. Where 72 DPI is no longer relevant, but you need to create a starting default for every setting regardless.

Fair enough!

wyeman wrote:

Thank you Adielle and Alcelc, that clears things up very well.

Question: If I print an image which is initially 75ppi and I change it to 300ppi in my image 2D software, how does the software decide what the additional pixels will look like?

There are no additional pixels. They will just be crammed into a smaller box. Unless you upsample in which case your image will have 16x the original number of pixels. I know only Photoshop CS4 where in image size you can tick a box called resize or something which gives a number of alternatives, 3 I think, which are called something fancy like bicubic interpolation or such. The versions are supposed to differ subtly in terms of prioritizing gradients or borders (local contrast, detail). I'm sure somebody can explain what actually happens but in any case the image won't look much more detailed, just not pixellated. With some judicial sharpening applied you might be able to make it look slightly crisper without introducing too obvious halos or other artefacts but 16MP is 16MP. My experience is that my GX7 gives me good A2 prints and haven't seen any difference between upsampling to 360ppi (optimized for the 1440dpi of my printer) in Photoshop or letting the printer take care of it. With more extreme magnification the situation might be different. I've tried to print 5MP files at A2 and imagine I got some improvement from upsampling and sharpening. They look ok from a distance but still fall apart at close scrutiny. I suggest you experiment.

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.

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

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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