Several manufacturers were rumored to launch a smartphone with a QHD-display (2560x1440 pixels) at Mobile World Congress in Barcelona
but none of the models introduced at the show featured one of the
high-resolution screens. Now the wait is over. The Chinese smartphone
manufacturer Oppo has introduced their latest flagship model, the Find
7. This makes the Find 7 the first smartphone to feature a QHD screen.
The pixel density of the 5.5-inch display is a staggering 538ppi which
should make for ultra-sharp rendering of images and text.
Not only
is the Find 7's screen top-notch, the new device comes with top-end
specifications all around. The Android OS is powered by a Snapdragon 801
SoC and 3GB RAM. Rapid Charge technology will let you charge the Find
7's 3000mAh battery to 75% in only 30 minutes and a MicroSD slot allows
for easy storage expansion.
The Camera
With a 13MP
1/3.06-inch Sony Exmor CMOS sensor and F2.0 aperture, the camera
specifications look decent, but not anything out of the ordinary. The
Find 7 also comes with a "Super Zoom" software feature that allows for
the capture of 50MP images. To achieve this the camera takes a burst of
10 images, then selects the four best shots and combines them into a
single 50MP frame. Brief communication with Oppo indicates they are
using a 'superposition' technique to create the 50MP file. We surmise
the underlying principle is similar to that used by the Hasselblad H4D-200MS to
create 200MP images from a 50MP sensor (note the similar 4x increase in
resolution over the native sensor resolution). Such super-resolution
techniques create a higher-than-native resolution image by relying on
small movements from shot-to-shot to allow for high frequency detail -
beyond what the sensor could natively represent accurately - to be
recovered. For example, consider the following example where the sensor
(indicated by the pixels outlined in red) is imaging black lines with
widths on par with pixel widths.
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An
illustrative example of a sensor's pixel grid (pixels outlined in red)
recording high frequency detail on par with the sensor's frequency. The
color (albeit black, white, or grey here) recorded at any pixel is shown
within each pixel. Graphic: Photo Acute
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Depending on the alignment of the sensor to these alternating black and white lines, the sensor may (left, in the image above) or may not
(right, in the image above) accurately represent the original pattern.
Remember: a pixel just tallies up the amount of light entering it, and
on the right, any pixel is just recording 50% white and 50% black - that
is, grey. This loss of contrast - resulting from the pattern being
averaged across pixels - results in a decrease in resolving ability of
high frequency detail. Now imagine shifting the sensor such that the
pixels on the right were to align with the pattern just as the pixels on
the left initially did in the example above. This might allow for the
recovery of additional detail. Sophisticated software algorithms can
'look' for this sort of detail across multiple shots to increase the
effective resolution of capture. Oddly enough, the small movements your
hands make from shot-to-shot - which you might initially imagine as
deleterious - end up potentially increasing the spatial resolution of
the sensor. Simply by allowing for many different alignments of the
sensor's pixel grid to the real-world detail being projected onto
it. You can read more about the basic principles of super-resolution and
how it is used to recover sub-pixel information in Photo Acute
software here.
We
do note that for this method to be effective, the lower 'native'
resolution images need to be aligned with sub-pixel precision. However,
with faster processors as well as accelerometer information regarding
shot-to-shot movements, we imagine this is not too large an issue with
modern hardware.
The 50MP Image - Any Good?
While Engadget shows
a sample that does not look too impressive at 100% view and has the
appearance of an upsampled file, the technique might have its merits in a
phone for creating a better, native 13MP resolution file
(downsampled from the 50MP file). Although Oppo confirmed that a lower,
'native' resolution output using their "Super Zoom" technology would not
be available (single shot 13MP - including RAW - output is still
available), users can always downsample the 50MP file to 13MP in any
photo-editing suite themselves. Furthermore, any multi-shot technique
has the potential to reduce noise - especially important for the small
sensors found in phones.
All that said, given the feature's "Super
Zoom" moniker we would expect the large images to, at the very least,
be used for a more efficient digital zoom. It'll be interesting to see
how it compares to Nokia's PureView and more conventional systems once
more samples are available.
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The Oppo Find 7 is the first smartphone with a QHD screen.
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The camera module comes with a 13MP Sony sensor and a F2.0 aperture.
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Further Details
In
addition the Oppo Find 7 is also the first Android device to offer Raw
capture. In video mode you can capture 4K footage and 120 fps slow
motion video at 720p resolution. For self-portraits and video-calls
there is a 5MP F2.0 front camera.
The Find 7 is also available as a
version with 1080p display that comes with a slightly downgraded CPU,
2GB RAM and less onboard-storage, but the camera specification is
identical to the QHD-model. The latter will retail at 3,498 CNY
(approximately $565), while the version with 1080p-screen will set you
back 2998 CNY (approximately $480). There is no word yet on availability
outside of China.
Key-specifications:
- Snapdragon 801 SoC
- 3GB RAM (1080p version: 2GB)
- 5.5-inch QHD (2560 x 1440 pixels) display, 538ppi (1080p version available, too)
- 32GB storage and MicroSD support (1080p version: 16GB)
- 13MP 1/3.06-inch Sony Exmor IMX214 sensor
- F2.0 lens
- 5MP F2.0 front camera
- Raw capture
- 4K video
- 720p 120 fps slow motion
- 3000mAh battery (1080p version: 2800mAh)
Source: Oppo
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