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Megapixels, resolution, lens, blah, blah....????
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Nov 16, 2020 10:03:13   #
SuperflyTNT Loc: Manassas VA
 
SuperflyTNT wrote:
If you stitched two 24mp shots there’s no way you got a 70mp image. The max you could get would by 48mp and only if the was no overlap. Were you looking at file size, (megabits), rather than resolution, (megapixels)? 70mb sounds reasonable for a file created by stitching two 24mp images.


Doh, I misread the OP. Yes 4 images could give you a 70mp image.

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Nov 16, 2020 10:26:14   #
DirtFarmer Loc: Escaped from the NYC area, back to MA
 
SuperflyTNT wrote:
Doh, I misread the OP. Yes 4 images could give you a 70mp image.


Actually I read it as 8 images. A horizontal row of 4 images on top of another horizontal row (which I assumed was also 4 images).

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Nov 16, 2020 10:30:30   #
lamiaceae Loc: San Luis Obispo County, CA
 
DirtFarmer wrote:
Resolution is the distance between lines that are far enough apart that you can tell that they are separate lines. The figures show two lines (red and blue crosses) and the sum, which is what the sensor would see.


Yes, that is optical resolution for lenses and film. Digital is a different animal.

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Nov 16, 2020 10:41:31   #
Fotoartist Loc: Detroit, Michigan
 
Gene51 wrote:
a stitched image is wider and taller than the same image taken with a single shot - so you have more megapixels and a wider field of view, but you get the convenience, and possible distortions of a single shot with a wide angle lens. If you had a 70 mp camera and you took a single image, with a wide angle lens, you may hit the limit of resolution for that sensor, making the image from the stitch likely better

The resolution would be 70 mp for the mythical camera, and whatever you end up with when you stitch.

The image below ended up being 14270x12404 px - or 177mp before downsampling for posting. It was a 5x3 array with a D800 and a 45mm lens.
a stitched image is wider and taller than the same... (show quote)


I never get tired of seeing this image.

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Nov 16, 2020 10:45:24   #
Fotoartist Loc: Detroit, Michigan
 
CHG_CANON wrote:
Pixel resolution of a digital image is always the total number of pixels, as expressed in pixels or mega pixels (MP). The calculation is simply the pixel-length * pixel-width / 1,000,000 = megapixels.

The image may have more megapixels due to the density of the sensor, but the field of view is the same for a given position and lens / focal length and sensor format. That is: compare full-frame to full-frame or 1.5 crop to 1.5 crop, etc.

So, if you stand at position 'x' and capture a subject at 'y' distance with the same lens at the same focal length with the same format camera (i.e., both full-frame), the more pixels provide the following options:

1) You can print a larger print-size at the same ppi (pixel per inch) resolution.

2) You can crop into the details of the image file and obtain a larger (or same) print from the larger pixel file than the smaller.

Example: 24MP image (6000x4000). If you want to print at 300ppi, this would print to 20x13-inches. The same image (same location, same distance, same focal length, sensor format) with a 54MP camera (9000x6000) would print to 30x20-inches at the same 300ppi. The image will have the same level of detail when inspected nose to print, but the print is 1.5-times larger.

Similarly, you can crop significantly into the 54MP image and still retain an image that prints to the same level of detail as the 24MP image at 300ppi, or fills the large-screen display monitor where the same crop from the 24MP sensor may no longer have enough pixels to still fill the screen when viewed full-screen.
Pixel resolution of a digital image is always the ... (show quote)


Your explanation seems clear in theory. And I am pretty sure it's true but has anyone given it the vision test in the real world and is the difference distinct?

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Nov 16, 2020 10:53:02   #
TriX Loc: Raleigh, NC
 
lamiaceae wrote:
MP for mega pixels

MB=Mb for Mega bytes

bits are 8, 16, 32, 64, etc.


Not to belabor this, but a “big B” is bytes (MB), and a “little b” is bits (Mb). 1 byte = 8 bits. MB is used to denote file/storage/memory size, while Mb is typically used to denote serial transfer rates. I’m sure you know all this, but just to clarify.

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Nov 16, 2020 11:12:43   #
rmalarz Loc: Tempe, Arizona
 
Thanks, TriX. Good information to share.
--Bob
TriX wrote:
Not to belabor this, but a “big B” is bytes (MB), and a “little b” is bits (Mb). 1 byte = 8 bits. MB is used to denote file/storage/memory size, while Mb is typically used to denote serial transfer rates. I’m sure you know all this, but just to clarify.

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Nov 16, 2020 11:19:56   #
CPR Loc: Nature Coast of Florida
 
If we're playing then a kilobyte is actually 1024 bits, not 1000 bits.....

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Nov 16, 2020 12:54:50   #
cbtsam Loc: Monkton, MD
 
Gene51 wrote:
a stitched image is wider and taller than the same image taken with a single shot - so you have more megapixels and a wider field of view, but you get the convenience, and possible distortions of a single shot with a wide angle lens. If you had a 70 mp camera and you took a single image, with a wide angle lens, you may hit the limit of resolution for that sensor, making the image from the stitch likely better

The resolution would be 70 mp for the mythical camera, and whatever you end up with when you stitch.

The image below ended up being 14270x12404 px - or 177mp before downsampling for posting. It was a 5x3 array with a D800 and a 45mm lens.
a stitched image is wider and taller than the same... (show quote)


Fascinating technological insights, Gene, but what I want to know is where you took you shot from.

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Nov 16, 2020 13:06:49   #
TriX Loc: Raleigh, NC
 
CPR wrote:
If we're playing then a kilobyte is actually 1024 bits, not 1000 bits.....


Depends.

“In December 1998, the IEC addressed such multiple usages and definitions by creating prefixes such as kibi, mebi, gibi, etc., to unambiguously denote powers of 1024.[10] Thus the kibibyte, symbol KiB, represents 210 bytes = 1024 bytes. These prefixes are now part of the International System of Quantities. The IEC further specified that the kilobyte should only be used to refer to 1000 bytes.”

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Nov 16, 2020 13:18:43   #
GrannyAnnie
 
CHG_CANON wrote:
Pixel resolution of a digital image is always the total number of pixels, as expressed in pixels or mega pixels (MP). The calculation is simply the pixel-length * pixel-width / 1,000,000 = megapixels.

The image may have more megapixels due to the density of the sensor, but the field of view is the same for a given position and lens / focal length and sensor format. That is: compare full-frame to full-frame or 1.5 crop to 1.5 crop, etc.

So, if you stand at position 'x' and capture a subject at 'y' distance with the same lens at the same focal length with the same format camera (i.e., both full-frame), the more pixels provide the following options:

1) You can print a larger print-size at the same ppi (pixel per inch) resolution.

2) You can crop into the details of the image file and obtain a larger (or same) print from the larger pixel file than the smaller.

Example: 24MP image (6000x4000). If you want to print at 300ppi, this would print to 20x13-inches. The same image (same location, same distance, same focal length, sensor format) with a 54MP camera (9000x6000) would print to 30x20-inches at the same 300ppi. The image will have the same level of detail when inspected nose to print, but the print is 1.5-times larger.

Similarly, you can crop significantly into the 54MP image and still retain an image that prints to the same level of detail as the 24MP image at 300ppi, or fills the large-screen display monitor where the same crop from the 24MP sensor may no longer have enough pixels to still fill the screen when viewed full-screen.
Pixel resolution of a digital image is always the ... (show quote)

For my remedial level, this is the clearest and most concise explanation I have read! Thank you!!

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Nov 16, 2020 14:22:30   #
DirtFarmer Loc: Escaped from the NYC area, back to MA
 
lamiaceae wrote:
Yes, that is optical resolution for lenses and film. Digital is a different animal.


Not really. The principle is the same. The graph might be misleading because there are so many points over each line. For a digital image there would be probably around 20 graph points per pixel.

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Nov 16, 2020 15:03:15   #
captainbinary
 
lamiaceae wrote:
MP for mega pixels

MB=Mb for Mega bytes

bits are 8, 16, 32, 64, etc.


Correction, MB = megabytes; Mb = megabits
kB = kilobytes; kb = kilobits
[K = Kelvin, the SI unit of temperature]

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Nov 16, 2020 15:22:00   #
dpullum Loc: Tampa Florida
 
bleirer wrote:
... Nice article on the topic of panorama https://www.cambridgeincolour.com/tutorials/digital-panoramas.htm


Bleirer, you ruined the fun by giving an authoritarian article that explains and gives calculators. Luckily, you were ignored else the conversation would have ended. I for one appreciated your injection of documented technical information... altho the rest of the discussions were thought-provoking and fun.

May I muddy the waters by suggesting that a program like Photozoom 7 will increase the resolution
"PhotoZoom Pro 8 not only creates larger images than any other software (up to 1 million by 1 million pixels), it also produces higher quality results. PhotoZoom Pro 8 is equipped with S-Spline Max, a unique, award-winning image resize technology which excels at preserving clean edges, sharpness, and fine details."
The program explained:
https://filmora.wondershare.com/photo-editing-tips/photozoom-review-resize-image.html

Comparison of 3 best current 2020 programs
https://reapon.com/photo-enlargement-software/

Ashampoo sells classic 7 for $20 a markdown price becuse it is not the current Photozoom 8.
https://shop.ashampoo.com/10/purl-onlineshop?cart=224760&usepricescale=false&x-source=web&x-mid=web&currency=GBP&coupon=F8H-9JD-Q27

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Nov 16, 2020 15:54:58   #
DocDav Loc: IN
 
24MP image (6000x4000). If you want to print at 300ppi, this would print to 20x13-inches. The same image (same location, same distance, same focal length, sensor format) with a 54MP camera (9000x6000) would print to 30x20-inches at the same 300ppi.

Is there a formula you use to calculate these enlargement figures? Or just experience?

Thanks

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