OCTA: A Practical Method of Image Averaging Using Adobe Photoshop Software

Abstract

BACKGROUND AND OBJECTIVE: To describe a method for averaging ocular coherence tomography angiography (OCTA) images using a commercially available photo editing software: Adobe Photoshop CC 2017. PATIENTS AND METHODS: This single-center study assessed the feasibility of using Adobe Photoshop as an OCTA image averaging tool. Three 3.0 mm × 3.0 mm OCTA images from each eye were obtained using commercially available OCTA devices. Captured OCTA images were exported in high-resolution TIFF format, imported as an image stack, aligned using an automated function, and averaged by creating a Smart Object using Photoshop CC 2017 software. In conjunction with qualitative assessment, the main outcome of the study was image grader preferences with respect to clarity of the foveal avascular zone (FAZ), blood vessel delineation, and the ability to identify abnormal vasculature. RESULTS: After removing OCTA scans with significant image distortion, 25 sets of images were included in the analysis. Adobe Photoshop CC 2017 successfully aligned and averaged all images of the superficial and deep retinal plexuses that contained a minimum 40% overlap. Three independent retinal specialists found the averaged images to be slightly or definitely preferable to the original 87%, 89%, and 69% of the time with respect to clarity of the FAZ, clarity of blood vessel delineation, and the ability to identify abnormal vasculature, respectively. CONCLUSIONS: Adobe Photoshop CC 2017 is an excellent tool for image averaging, producing high-quality resulting OCTA images. As an easily accessible software, Photoshop has the potential for use in a diversity of pathological conditions. [ Ophthalmic Surg Lasers Imaging Retina . 2019;50:802–807.]

An Improved Method Research on Graphics and Image Processing System

“…It not only brings convenience to people but also brings worry to us [6]. Digital images are very vulnerable to external "attacks," and the society pays more and more attention to and questions the requirements for the authenticity and integrity of digital images [7].…”

Effect of caffeine on superficial retinal vasculature of the macula in high myopes using optical coherence tomography angiography – A pilot study

“…Although OCTA is now commonly used in ophthalmic practice, this technology is limited by severe artefacts, including shadow, defocus, and movement artefacts during acquisition. 49 Averaging multiple OCTA acquisitions could enhance image quality 50 51 and be more sensitive in detecting differences, 52 especially when the scan size is large (such as 6 × 6 mm) with low resolution in pixel/mm. 53 Previous studies have documented the advantage of image averaging in examining retinal vein occlusion 54 and diabetic retinopathy.…”

Assessing the Influence of OCT-A Device and Scan Size on Retinal Vascular Metrics

“…53 This tradeoff can be compensated for via montaging multiple smaller high-quality images or by utilizing frame averaging with larger images to improve the signalto-noise ratio. 4,[36][37][38][39] Whereas montaging and averaging are feasible in a research setting, they have not yet reached widespread use -this can be remedied with software advances. Future studies may be able to identify the optimal scan size that gives reliable measures of vessel morphometry without sacrificing the scan area.…”

“…35 In studies comparing scan size, the issue of image magnification is less critical, as we are only interested in relative differences between scan dimensions from the same device. However, it is known that averaging multiple en face OCT-A images can significantly improve signal-tonoise ratio; 4,[36][37][38][39] thus the use of averaged images could allow a more direct evaluation of the impact of scan size on quantitative vascular metrics. This is important, as multiple studies have found that the reliability and/or repeatability of various vascular metrics tends to be worse for larger scan sizes.…”