Image Quality and Performance

With its high-end specification and powerful Snapdragon 801 quad-core SoC the HTC One M8 feels very fast and responsive in general use, with apps opening and operating swiftly and screens and images scrolling smoothly on the large screen. 

The HTC also performs responsively when using the camera. It takes just over a second for the camera app to open and be ready for your first capture. Shot to shot times are very fast, you can practically shoot as fast as you can move your finger up and down on the shutter button. A long press on the shutter triggers a burst of 20 images within approximately two seconds. Unfortunately continuous shooting cannot be combined with manual mode and it is therefore, like on most smartphones, not possible to set shutter speeds fast enough to freeze motion in lower light.

Focus acquisition is in line with competing devices but, due to the lack of a focus light, slows down a lot in low light. In very dim conditions occasionally the One M8's focus will lock despite the image being out of focus, capturing a blurry image. It's not quite clear why HTC does not use the flash LEDs as a focus assist light, like many other smarpthones on the market. 

Daylight, Low ISO

The lowest ISO that can be selected manually is 200 but in Auto mode and in good light the HTC One M8 captures most images at ISO 125. Very occasionally an image is tagged as ISO 100 in the Exif-data but there is no discernible difference in terms of image quality. 

Apart from some shadow noise the low ISO images are quite saturated and clean, with only very little visible noise in areas of plain color, such as skies. However, the HTC's 4MP and F2 lens resolve visibly less detail than the competing high-end devices with their higher-resolution sensors. Sharpening is strong but within acceptable limits. Like on most smartphones there is some smearing of low-contrast detail, even at base ISO.

ISO 125, 1/3932 sec 
ISO 100, 1/533 sec 
100% crop
100% crop

When taking images of sunny scenes we have noticed that the HTC's exposure is often a touch darker than other devices, presumably in an attempt to protect the highlights from clipping. However, it seems HTC is slightly overdoing things. When looking at the histogram of the out-of-camera image below you can see that the exposure is shifted toward the dark tones, with few highlights. After a quick level-adjustment in Photoshop the image's tones are distributed across the entire tonal range and the exposure is more pleasant.  

ISO 125, 1/7865 sec, out of camera
After level-adjustment
Histogram, out of camera
Histogram, after level-adjustment in Photoshop

The HTC One M8 is extremely prone to moiré artifacts. If there are fine repeating patterns in your scene there is a good chance you will end up with moiré in your images. The effect ranges from fairly subtle, like in the roof tiles of the building in the left image below, to very extreme, like on the striped T-shirt worn by the person in the image on the right. Unfortunately there is very little you can do to avoid this.

ISO 125, 1/2420 sec
ISO 125, 1/375 sec
100% crop
100% crop

Fringing is another problem. You'll find it on the typical high-contrast edges and often in doses that make it visible even at smaller viewing sizes. Most digital cameras and smartphones use software algorithms to get rid of or at least mitigate the effect but it appears no such system has been implemented on the One M8. In some of the examples we've shot, it's hard to separate moiré from fringing, and it's possible that in some areas (like the ones we're showing below) the obvious false colors result from a combination of issues.

ISO 125, 1/3932 sec
ISO 125, 1/5243 sec
100% crop
100% crop

Like on all smartphones the One M8's dynamic range is limited and the camera struggles with highlights in high-contrast scenes. In practice this means that on a bright day smartphones have a tendency to clip highlight in the sky, especially if the landscape portion of the frame is darker.

While this is common to almost all smartphones the One M8 has the additional nasty habit of only clipping one or two color channels and turning the sky cyan before clipping completely. This gives the image a very unnatural look and we would not expect to see this on any digital camera in 2014.   

ISO 125, 1/2622 sec
ISO 125, 1/2247 sec
100% crop
100% crop

Low Light, High ISO

Thanks to its fast lens and a tendency to use slow shutter speeds the HTC One M8 can keep the ISO at base until the light conditions get quite dim. For the images below, which were shot indoors at fairly low light levels, the camera only had to increase ISO to 250 and 320 respectively. For the second image the camera could have kept the ISO even lower as a shutter speed of 1/100 sec is much faster than what the One M8 usually tends to pick in these conditions.

At those moderate ISO levels the images already start losing some fine detail and there is some chroma noise visible in the shadow areas but overall they still look good at screen viewing size, with good exposure and colors.

ISO 250, 1/17 sec
ISO 320, 1/100 sec
100% crop
100% crop

Climbing up the ISO ladder the loss of fine detail becomes more obvious. Fine detail, like hair or the feathers in the image on the right, is being blurred by noise reduction. Yet both luminance and chroma noise become more visible in shadow areas and areas of plain color. In these low light conditions the HTC uses shutter speeds of around 1/12 sec which will cause motion blur even on very slow moving subjects.

ISO 500, 1/14 sec
ISO 640, 1/12 sec
100% crop
100% crop

In this dark church the camera had to increase ISO to 1250 and 1600 respectively and when zooming in to 100% view it's very obvious that such high settings take their toll. There is practically no fine detail left in the images which are also blighted by an ugly mix of noise and artifacts. If your image quality requirements are not too high these images are still usable at smaller viewing sizes but you would not want to use them for making a framed print. 

ISO 1250, 1/11 sec, -1EV
ISO 1600, 1/11 sec
100% crop
100% crop

The images below have been taken in very low light and the HTC uses its highest ISO setting of 3200. It's commendable that the One M8 can still achieve a decent exposure in these conditions but very high levels of noise and softness caused by noise reduction limit the use of these images to documentary purposes.

ISO 3200, 1/11 sec
ISO 3200, 1/11 sec
100% crop
100% crop

Flash

The One M8 generally does a good job when flash is used but in common with previous HTC models we have tested it delivers relatively dark exposures. This helps in keeping the ISO down though and at ISO 250 for the sample below more detail is preserved than on some competitors that use higher ISOs in flash mode.

The dual-LED system helps avoid the typical cool color cast we've seen on flash images taken with previous generation smartphones but the HTC has one important disadvantage: it does not use the flash LED as a focus light in low light which means the focus can be very slow to lock on and occasionally do so when the image is not actually in focus, as can be see in the sample to the right. 

ISO 250, 1/12 sec
ISO 250, 1/17 sec
100% crop
100% crop

Digital Zoom

With the exception of the latest generation of Nokia Lumia devices and within limits the Sony Xperia Z1 and Z1 using the digital zoom on any smartphone is generally a bad idea. However, due to its low 4MP pixel count the HTC One M8 is particularly bad. As you see below image quality heads south as soon as you touch the zoom control. The maximum 4x setting creates a pixelated mess and in our opinion should not even be offered as on option on this phone.

No zoom 
100% crop
2x zoom
100% crop
4x zoom
100% crop